Revert of Removing #defines previously used for building without BoringSSL/OpenSSL. (patchset #2 id:20001 of https://codereview.webrtc.org/2640513002/ )

Reason for revert:
Broke chromium build, due to a config being removed. Will add it back and remove the dependency in a chromium CL.

Original issue's description:
> Removing #defines previously used for building without BoringSSL/OpenSSL.
>
> These defines don't work any more, so they only cause confusion:
>
> FEATURE_ENABLE_SSL
> HAVE_OPENSSL_SSL_H
> SSL_USE_OPENSSL
>
> BUG=webrtc:7025
>
> Review-Url: https://codereview.webrtc.org/2640513002
> Cr-Commit-Position: refs/heads/master@{#16196}
> Committed: https://chromium.googlesource.com/external/webrtc/+/eaa826c2ee0668cfb4a0dfb66f8d388b65da20f5

TBR=kjellander@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7025

Review-Url: https://codereview.webrtc.org/2648003003
Cr-Commit-Position: refs/heads/master@{#16197}
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index 1a68b3a..51882da 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -35,10 +35,21 @@
   }
 }
 
+config("rtc_base_config") {
+  defines = [ "FEATURE_ENABLE_SSL" ]
+}
+
 config("rtc_base_chromium_config") {
   defines = [ "NO_MAIN_THREAD_WRAPPING" ]
 }
 
+config("openssl_config") {
+  defines = [
+    "SSL_USE_OPENSSL",
+    "HAVE_OPENSSL_SSL_H",
+  ]
+}
+
 config("rtc_base_all_dependent_config") {
   if (is_ios) {
     libs = [
@@ -360,6 +371,16 @@
     ":rtc_base_approved",
   ]
 
+  configs += [
+    ":openssl_config",
+    ":rtc_base_config",
+  ]
+
+  public_configs = [
+    ":openssl_config",
+    ":rtc_base_config",
+  ]
+
   all_dependent_configs = [ ":rtc_base_all_dependent_config" ]
 
   sources = [
@@ -516,6 +537,7 @@
       "proxyserver.h",
       "rollingaccumulator.h",
       "scopedptrcollection.h",
+      "sslconfig.h",
       "sslroots.h",
       "testbase64.h",
       "testclient.cc",
diff --git a/webrtc/base/helpers.cc b/webrtc/base/helpers.cc
index aa6a6ae..a8389d4 100644
--- a/webrtc/base/helpers.cc
+++ b/webrtc/base/helpers.cc
@@ -13,7 +13,18 @@
 #include <limits>
 #include <memory>
 
+#if defined(FEATURE_ENABLE_SSL)
+#include "webrtc/base/sslconfig.h"
+#if defined(SSL_USE_OPENSSL)
 #include <openssl/rand.h>
+#else
+#if defined(WEBRTC_WIN)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <ntsecapi.h>
+#endif  // WEBRTC_WIN
+#endif  // else
+#endif  // FEATURE_ENABLED_SSL
 
 #include "webrtc/base/base64.h"
 #include "webrtc/base/basictypes.h"
@@ -34,6 +45,7 @@
   virtual bool Generate(void* buf, size_t len) = 0;
 };
 
+#if defined(SSL_USE_OPENSSL)
 // The OpenSSL RNG.
 class SecureRandomGenerator : public RandomGenerator {
  public:
@@ -45,6 +57,79 @@
   }
 };
 
+#else
+#if defined(WEBRTC_WIN)
+class SecureRandomGenerator : public RandomGenerator {
+ public:
+  SecureRandomGenerator() : advapi32_(NULL), rtl_gen_random_(NULL) {}
+  ~SecureRandomGenerator() {
+    FreeLibrary(advapi32_);
+  }
+
+  virtual bool Init(const void* seed, size_t seed_len) {
+    // We don't do any additional seeding on Win32, we just use the CryptoAPI
+    // RNG (which is exposed as a hidden function off of ADVAPI32 so that we
+    // don't need to drag in all of CryptoAPI)
+    if (rtl_gen_random_) {
+      return true;
+    }
+
+    advapi32_ = LoadLibrary(L"advapi32.dll");
+    if (!advapi32_) {
+      return false;
+    }
+
+    rtl_gen_random_ = reinterpret_cast<RtlGenRandomProc>(
+        GetProcAddress(advapi32_, "SystemFunction036"));
+    if (!rtl_gen_random_) {
+      FreeLibrary(advapi32_);
+      return false;
+    }
+
+    return true;
+  }
+  virtual bool Generate(void* buf, size_t len) {
+    if (!rtl_gen_random_ && !Init(NULL, 0)) {
+      return false;
+    }
+    return (rtl_gen_random_(buf, static_cast<int>(len)) != FALSE);
+  }
+
+ private:
+  typedef BOOL (WINAPI *RtlGenRandomProc)(PVOID, ULONG);
+  HINSTANCE advapi32_;
+  RtlGenRandomProc rtl_gen_random_;
+};
+
+#elif !defined(FEATURE_ENABLE_SSL)
+
+// No SSL implementation -- use rand()
+class SecureRandomGenerator : public RandomGenerator {
+ public:
+  virtual bool Init(const void* seed, size_t len) {
+    if (len >= 4) {
+      srand(*reinterpret_cast<const int*>(seed));
+    } else {
+      srand(*reinterpret_cast<const char*>(seed));
+    }
+    return true;
+  }
+  virtual bool Generate(void* buf, size_t len) {
+    char* bytes = reinterpret_cast<char*>(buf);
+    for (size_t i = 0; i < len; ++i) {
+      bytes[i] = static_cast<char>(rand());
+    }
+    return true;
+  }
+};
+
+#else
+
+#error No SSL implementation has been selected!
+
+#endif  // WEBRTC_WIN
+#endif
+
 // A test random generator, for predictable output.
 class TestRandomGenerator : public RandomGenerator {
  public:
diff --git a/webrtc/base/messagedigest.cc b/webrtc/base/messagedigest.cc
index 5e8621c..c08cab4 100644
--- a/webrtc/base/messagedigest.cc
+++ b/webrtc/base/messagedigest.cc
@@ -15,7 +15,13 @@
 #include <string.h>
 
 #include "webrtc/base/basictypes.h"
+#include "webrtc/base/sslconfig.h"
+#if SSL_USE_OPENSSL
 #include "webrtc/base/openssldigest.h"
+#else
+#include "webrtc/base/md5digest.h"
+#include "webrtc/base/sha1digest.h"
+#endif
 #include "webrtc/base/stringencode.h"
 
 namespace rtc {
@@ -31,12 +37,22 @@
 static const size_t kBlockSize = 64;  // valid for SHA-256 and down
 
 MessageDigest* MessageDigestFactory::Create(const std::string& alg) {
+#if SSL_USE_OPENSSL
   MessageDigest* digest = new OpenSSLDigest(alg);
   if (digest->Size() == 0) {  // invalid algorithm
     delete digest;
     digest = NULL;
   }
   return digest;
+#else
+  MessageDigest* digest = NULL;
+  if (alg == DIGEST_MD5) {
+    digest = new Md5Digest();
+  } else if (alg == DIGEST_SHA_1) {
+    digest = new Sha1Digest();
+  }
+  return digest;
+#endif
 }
 
 bool IsFips180DigestAlgorithm(const std::string& alg) {
diff --git a/webrtc/base/openssladapter.cc b/webrtc/base/openssladapter.cc
index d368186..4301916 100644
--- a/webrtc/base/openssladapter.cc
+++ b/webrtc/base/openssladapter.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#if HAVE_OPENSSL_SSL_H
+
 #include "webrtc/base/openssladapter.h"
 
 #if defined(WEBRTC_POSIX)
@@ -963,3 +965,5 @@
 }
 
 } // namespace rtc
+
+#endif  // HAVE_OPENSSL_SSL_H
diff --git a/webrtc/base/openssldigest.cc b/webrtc/base/openssldigest.cc
index 0413f8f..2618b7f 100644
--- a/webrtc/base/openssldigest.cc
+++ b/webrtc/base/openssldigest.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#if HAVE_OPENSSL_SSL_H
+
 #include "webrtc/base/openssldigest.h"
 
 #include "webrtc/base/checks.h"
@@ -116,3 +118,5 @@
 }
 
 }  // namespace rtc
+
+#endif  // HAVE_OPENSSL_SSL_H
diff --git a/webrtc/base/opensslidentity.cc b/webrtc/base/opensslidentity.cc
index 7b96f6a..2f1c565 100644
--- a/webrtc/base/opensslidentity.cc
+++ b/webrtc/base/opensslidentity.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#if HAVE_OPENSSL_SSL_H
+
 #include "webrtc/base/opensslidentity.h"
 
 #include <memory>
@@ -574,3 +576,5 @@
 }
 
 }  // namespace rtc
+
+#endif  // HAVE_OPENSSL_SSL_H
diff --git a/webrtc/base/opensslstreamadapter.cc b/webrtc/base/opensslstreamadapter.cc
index 158315f..3b3aa5d 100644
--- a/webrtc/base/opensslstreamadapter.cc
+++ b/webrtc/base/opensslstreamadapter.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#if HAVE_OPENSSL_SSL_H
+
 #include "webrtc/base/opensslstreamadapter.h"
 
 #include <openssl/bio.h>
@@ -43,10 +45,11 @@
 
 namespace rtc {
 
-#if (OPENSSL_VERSION_NUMBER < 0x10001000L)
-#error "webrtc requires at least OpenSSL version 1.0.1, to support DTLS-SRTP"
+#if (OPENSSL_VERSION_NUMBER >= 0x10001000L)
+#define HAVE_DTLS_SRTP
 #endif
 
+#ifdef HAVE_DTLS_SRTP
 // SRTP cipher suite table. |internal_name| is used to construct a
 // colon-separated profile strings which is needed by
 // SSL_CTX_set_tlsext_use_srtp().
@@ -62,6 +65,7 @@
     {"SRTP_AEAD_AES_128_GCM", SRTP_AEAD_AES_128_GCM},
     {"SRTP_AEAD_AES_256_GCM", SRTP_AEAD_AES_256_GCM},
     {nullptr, 0}};
+#endif
 
 #ifdef OPENSSL_IS_BORINGSSL
 // Not used in production code. Actual time should be relative to Jan 1, 1970.
@@ -428,6 +432,7 @@
                                                 bool use_context,
                                                 uint8_t* result,
                                                 size_t result_len) {
+#ifdef HAVE_DTLS_SRTP
   int i;
 
   i = SSL_export_keying_material(ssl_, result, result_len, label.c_str(),
@@ -438,10 +443,14 @@
     return false;
 
   return true;
+#else
+  return false;
+#endif
 }
 
 bool OpenSSLStreamAdapter::SetDtlsSrtpCryptoSuites(
     const std::vector<int>& ciphers) {
+#ifdef HAVE_DTLS_SRTP
   std::string internal_ciphers;
 
   if (state_ != SSL_NONE)
@@ -472,9 +481,13 @@
 
   srtp_ciphers_ = internal_ciphers;
   return true;
+#else
+  return false;
+#endif
 }
 
 bool OpenSSLStreamAdapter::GetDtlsSrtpCryptoSuite(int* crypto_suite) {
+#ifdef HAVE_DTLS_SRTP
   RTC_DCHECK(state_ == SSL_CONNECTED);
   if (state_ != SSL_CONNECTED)
     return false;
@@ -488,6 +501,9 @@
   *crypto_suite = srtp_profile->id;
   RTC_DCHECK(!SrtpCryptoSuiteToName(*crypto_suite).empty());
   return true;
+#else
+  return false;
+#endif
 }
 
 bool OpenSSLStreamAdapter::IsTlsConnected() {
@@ -1080,12 +1096,14 @@
   SSL_CTX_set_cipher_list(ctx,
       "DEFAULT:!NULL:!aNULL:!SHA256:!SHA384:!aECDH:!AESGCM+AES256:!aPSK");
 
+#ifdef HAVE_DTLS_SRTP
   if (!srtp_ciphers_.empty()) {
     if (SSL_CTX_set_tlsext_use_srtp(ctx, srtp_ciphers_.c_str())) {
       SSL_CTX_free(ctx);
       return NULL;
     }
   }
+#endif
 
   return ctx;
 }
@@ -1151,6 +1169,26 @@
   return stream->VerifyPeerCertificate();
 }
 
+bool OpenSSLStreamAdapter::HaveDtls() {
+  return true;
+}
+
+bool OpenSSLStreamAdapter::HaveDtlsSrtp() {
+#ifdef HAVE_DTLS_SRTP
+  return true;
+#else
+  return false;
+#endif
+}
+
+bool OpenSSLStreamAdapter::HaveExporter() {
+#ifdef HAVE_DTLS_SRTP
+  return true;
+#else
+  return false;
+#endif
+}
+
 bool OpenSSLStreamAdapter::IsBoringSsl() {
 #ifdef OPENSSL_IS_BORINGSSL
   return true;
@@ -1235,3 +1273,5 @@
 }
 
 }  // namespace rtc
+
+#endif  // HAVE_OPENSSL_SSL_H
diff --git a/webrtc/base/opensslstreamadapter.h b/webrtc/base/opensslstreamadapter.h
index d3edf3a..e7d2174 100644
--- a/webrtc/base/opensslstreamadapter.h
+++ b/webrtc/base/opensslstreamadapter.h
@@ -109,7 +109,10 @@
 
   bool IsTlsConnected() override;
 
-  // Capabilities interfaces.
+  // Capabilities interfaces
+  static bool HaveDtls();
+  static bool HaveDtlsSrtp();
+  static bool HaveExporter();
   static bool IsBoringSsl();
 
   static bool IsAcceptableCipher(int cipher, KeyType key_type);
diff --git a/webrtc/base/ssladapter.cc b/webrtc/base/ssladapter.cc
index 06fce54..ba24e61 100644
--- a/webrtc/base/ssladapter.cc
+++ b/webrtc/base/ssladapter.cc
@@ -10,7 +10,13 @@
 
 #include "webrtc/base/ssladapter.h"
 
-#include "webrtc/base/openssladapter.h"
+#include "webrtc/base/sslconfig.h"
+
+#if SSL_USE_OPENSSL
+
+#include "openssladapter.h"
+
+#endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ -18,11 +24,18 @@
 
 SSLAdapter*
 SSLAdapter::Create(AsyncSocket* socket) {
+#if SSL_USE_OPENSSL
   return new OpenSSLAdapter(socket);
+#else  // !SSL_USE_OPENSSL
+  delete socket;
+  return NULL;
+#endif  // SSL_USE_OPENSSL
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#if SSL_USE_OPENSSL
+
 bool InitializeSSL(VerificationCallback callback) {
   return OpenSSLAdapter::InitializeSSL(callback);
 }
@@ -35,6 +48,22 @@
   return OpenSSLAdapter::CleanupSSL();
 }
 
+#else  // !SSL_USE_OPENSSL
+
+bool InitializeSSL(VerificationCallback callback) {
+  return true;
+}
+
+bool InitializeSSLThread() {
+  return true;
+}
+
+bool CleanupSSL() {
+  return true;
+}
+
+#endif  // SSL_USE_OPENSSL
+
 ///////////////////////////////////////////////////////////////////////////////
 
 }  // namespace rtc
diff --git a/webrtc/base/ssladapter_unittest.cc b/webrtc/base/ssladapter_unittest.cc
index c591f19..a6ec56e 100644
--- a/webrtc/base/ssladapter_unittest.cc
+++ b/webrtc/base/ssladapter_unittest.cc
@@ -370,6 +370,8 @@
       : SSLAdapterTestBase(rtc::SSL_MODE_DTLS, rtc::KeyParams::ECDSA()) {}
 };
 
+#if SSL_USE_OPENSSL
+
 // Basic tests: TLS
 
 // Test that handshake works, using RSA
@@ -417,3 +419,5 @@
   TestHandshake(true);
   TestTransfer("Hello, world!");
 }
+
+#endif  // SSL_USE_OPENSSL
diff --git a/webrtc/base/sslconfig.h b/webrtc/base/sslconfig.h
new file mode 100644
index 0000000..6aabad0
--- /dev/null
+++ b/webrtc/base/sslconfig.h
@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2012 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_SSLCONFIG_H_
+#define WEBRTC_BASE_SSLCONFIG_H_
+
+// If no preference has been indicated, default to SChannel on Windows and
+// OpenSSL everywhere else, if it is available.
+#if !defined(SSL_USE_SCHANNEL) && !defined(SSL_USE_OPENSSL)
+#if defined(WEBRTC_WIN)
+
+#define SSL_USE_SCHANNEL 1
+
+#else  // defined(WEBRTC_WIN)
+
+#if defined(HAVE_OPENSSL_SSL_H)
+#define SSL_USE_OPENSSL 1
+#endif
+
+#endif  // !defined(WEBRTC_WIN)
+#endif
+
+#endif  // WEBRTC_BASE_SSLCONFIG_H_
diff --git a/webrtc/base/sslidentity.cc b/webrtc/base/sslidentity.cc
index a5dd7b9..645050a 100644
--- a/webrtc/base/sslidentity.cc
+++ b/webrtc/base/sslidentity.cc
@@ -17,9 +17,15 @@
 #include "webrtc/base/base64.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
-#include "webrtc/base/opensslidentity.h"
+#include "webrtc/base/sslconfig.h"
 #include "webrtc/base/sslfingerprint.h"
 
+#if SSL_USE_OPENSSL
+
+#include "webrtc/base/opensslidentity.h"
+
+#endif  // SSL_USE_OPENSSL
+
 namespace rtc {
 
 const char kPemTypeCertificate[] = "CERTIFICATE";
@@ -207,6 +213,8 @@
   std::for_each(certs_.begin(), certs_.end(), DeleteCert);
 }
 
+#if SSL_USE_OPENSSL
+
 // static
 SSLCertificate* SSLCertificate::FromPEMString(const std::string& pem_string) {
   return OpenSSLCertificate::FromPEMString(pem_string);
@@ -252,6 +260,12 @@
   return !(a == b);
 }
 
+#else  // !SSL_USE_OPENSSL
+
+#error "No SSL implementation"
+
+#endif  // SSL_USE_OPENSSL
+
 // Read |n| bytes from ASN1 number string at *|pp| and return the numeric value.
 // Update *|pp| and *|np| to reflect number of read bytes.
 static inline int ASN1ReadInt(const unsigned char** pp, size_t* np, size_t n) {
diff --git a/webrtc/base/sslstreamadapter.cc b/webrtc/base/sslstreamadapter.cc
index 2f601c6..c3ef3bc 100644
--- a/webrtc/base/sslstreamadapter.cc
+++ b/webrtc/base/sslstreamadapter.cc
@@ -9,9 +9,14 @@
  */
 
 #include "webrtc/base/sslstreamadapter.h"
+#include "webrtc/base/sslconfig.h"
+
+#if SSL_USE_OPENSSL
 
 #include "webrtc/base/opensslstreamadapter.h"
 
+#endif  // SSL_USE_OPENSSL
+
 ///////////////////////////////////////////////////////////////////////////////
 
 namespace rtc {
@@ -96,7 +101,11 @@
 }
 
 SSLStreamAdapter* SSLStreamAdapter::Create(StreamInterface* stream) {
+#if SSL_USE_OPENSSL
   return new OpenSSLStreamAdapter(stream);
+#else  // !SSL_USE_OPENSSL
+  return NULL;
+#endif  // SSL_USE_OPENSSL
 }
 
 SSLStreamAdapter::SSLStreamAdapter(StreamInterface* stream)
@@ -128,6 +137,16 @@
   return false;
 }
 
+#if SSL_USE_OPENSSL
+bool SSLStreamAdapter::HaveDtls() {
+  return OpenSSLStreamAdapter::HaveDtls();
+}
+bool SSLStreamAdapter::HaveDtlsSrtp() {
+  return OpenSSLStreamAdapter::HaveDtlsSrtp();
+}
+bool SSLStreamAdapter::HaveExporter() {
+  return OpenSSLStreamAdapter::HaveExporter();
+}
 bool SSLStreamAdapter::IsBoringSsl() {
   return OpenSSLStreamAdapter::IsBoringSsl();
 }
@@ -144,6 +163,7 @@
 void SSLStreamAdapter::enable_time_callback_for_testing() {
   OpenSSLStreamAdapter::enable_time_callback_for_testing();
 }
+#endif  // SSL_USE_OPENSSL
 
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/webrtc/base/sslstreamadapter.h b/webrtc/base/sslstreamadapter.h
index 4f5ee02..3910191 100644
--- a/webrtc/base/sslstreamadapter.h
+++ b/webrtc/base/sslstreamadapter.h
@@ -228,9 +228,10 @@
   // SS_OPENING but IsTlsConnected should return true.
   virtual bool IsTlsConnected() = 0;
 
-  // Capabilities testing.
-  // Used to have "DTLS supported", "DTLS-SRTP supported" etc. methods, but now
-  // that's assumed.
+  // Capabilities testing
+  static bool HaveDtls();
+  static bool HaveDtlsSrtp();
+  static bool HaveExporter();
   static bool IsBoringSsl();
 
   // Returns true iff the supplied cipher is deemed to be strong.
diff --git a/webrtc/base/sslstreamadapter_unittest.cc b/webrtc/base/sslstreamadapter_unittest.cc
index 8203691..9d73abc 100644
--- a/webrtc/base/sslstreamadapter_unittest.cc
+++ b/webrtc/base/sslstreamadapter_unittest.cc
@@ -19,6 +19,7 @@
 #include "webrtc/base/gunit.h"
 #include "webrtc/base/helpers.h"
 #include "webrtc/base/ssladapter.h"
+#include "webrtc/base/sslconfig.h"
 #include "webrtc/base/sslidentity.h"
 #include "webrtc/base/sslstreamadapter.h"
 #include "webrtc/base/stream.h"
@@ -64,6 +65,12 @@
     "UD0A8qfhfDM+LK6rPAnCsVN0NRDY3jvd6rzix9M=\n"
     "-----END CERTIFICATE-----\n";
 
+#define MAYBE_SKIP_TEST(feature)                    \
+  if (!(rtc::SSLStreamAdapter::feature())) {  \
+    LOG(LS_INFO) << "Feature disabled... skipping"; \
+    return;                                         \
+  }
+
 class SSLStreamAdapterTestBase;
 
 class SSLDummyStreamBase : public rtc::StreamInterface,
@@ -956,6 +963,7 @@
 // Basic tests: DTLS
 // Test that we can make a handshake work
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSConnect) {
+  MAYBE_SKIP_TEST(HaveDtls);
   TestHandshake();
 };
 
@@ -963,12 +971,14 @@
 // each direction is lost. This gives us predictable loss
 // rather than having to tune random
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSConnectWithLostFirstPacket) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetLoseFirstPacket(true);
   TestHandshake();
 };
 
 // Test a handshake with loss and delay
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSConnectWithLostFirstPacketDelay2s) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetLoseFirstPacket(true);
   SetDelay(2000);
   SetHandshakeWait(20000);
@@ -978,6 +988,7 @@
 // Test a handshake with small MTU
 // Disabled due to https://code.google.com/p/webrtc/issues/detail?id=3910
 TEST_P(SSLStreamAdapterTestDTLS, DISABLED_TestDTLSConnectWithSmallMtu) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetMtu(700);
   SetHandshakeWait(20000);
   TestHandshake();
@@ -985,17 +996,20 @@
 
 // Test transfer -- trivial
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSTransfer) {
+  MAYBE_SKIP_TEST(HaveDtls);
   TestHandshake();
   TestTransfer(100);
 };
 
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSTransferWithLoss) {
+  MAYBE_SKIP_TEST(HaveDtls);
   TestHandshake();
   SetLoss(10);
   TestTransfer(100);
 };
 
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSTransferWithDamage) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetDamage();  // Must be called first because first packet
                 // write happens at end of handshake.
   TestHandshake();
@@ -1012,6 +1026,7 @@
 
 // Test DTLS-SRTP with all high ciphers
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpHigh) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> high;
   high.push_back(rtc::SRTP_AES128_CM_SHA1_80);
   SetDtlsSrtpCryptoSuites(high, true);
@@ -1029,6 +1044,7 @@
 
 // Test DTLS-SRTP with all low ciphers
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpLow) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> low;
   low.push_back(rtc::SRTP_AES128_CM_SHA1_32);
   SetDtlsSrtpCryptoSuites(low, true);
@@ -1046,6 +1062,7 @@
 
 // Test DTLS-SRTP with a mismatch -- should not converge
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpHighLow) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> high;
   high.push_back(rtc::SRTP_AES128_CM_SHA1_80);
   std::vector<int> low;
@@ -1062,6 +1079,7 @@
 
 // Test DTLS-SRTP with each side being mixed -- should select high
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpMixed) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> mixed;
   mixed.push_back(rtc::SRTP_AES128_CM_SHA1_80);
   mixed.push_back(rtc::SRTP_AES128_CM_SHA1_32);
@@ -1080,6 +1098,7 @@
 
 // Test DTLS-SRTP with all GCM-128 ciphers.
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpGCM128) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> gcm128;
   gcm128.push_back(rtc::SRTP_AEAD_AES_128_GCM);
   SetDtlsSrtpCryptoSuites(gcm128, true);
@@ -1097,6 +1116,7 @@
 
 // Test DTLS-SRTP with all GCM-256 ciphers.
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpGCM256) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> gcm256;
   gcm256.push_back(rtc::SRTP_AEAD_AES_256_GCM);
   SetDtlsSrtpCryptoSuites(gcm256, true);
@@ -1114,6 +1134,7 @@
 
 // Test DTLS-SRTP with mixed GCM-128/-256 ciphers -- should not converge.
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpGCMMismatch) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> gcm128;
   gcm128.push_back(rtc::SRTP_AEAD_AES_128_GCM);
   std::vector<int> gcm256;
@@ -1130,6 +1151,7 @@
 
 // Test DTLS-SRTP with both GCM-128/-256 ciphers -- should select GCM-256.
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSSrtpGCMMixed) {
+  MAYBE_SKIP_TEST(HaveDtlsSrtp);
   std::vector<int> gcmBoth;
   gcmBoth.push_back(rtc::SRTP_AEAD_AES_256_GCM);
   gcmBoth.push_back(rtc::SRTP_AEAD_AES_128_GCM);
@@ -1177,6 +1199,7 @@
 
 // Test an exporter
 TEST_P(SSLStreamAdapterTestDTLS, TestDTLSExporter) {
+  MAYBE_SKIP_TEST(HaveExporter);
   TestHandshake();
   unsigned char client_out[20];
   unsigned char server_out[20];
@@ -1199,6 +1222,7 @@
 
 // Test not yet valid certificates are not rejected.
 TEST_P(SSLStreamAdapterTestDTLS, TestCertNotYetValid) {
+  MAYBE_SKIP_TEST(HaveDtls);
   long one_day = 60 * 60 * 24;
   // Make the certificates not valid until one day later.
   ResetIdentitiesWithValidity(one_day, one_day);
@@ -1207,6 +1231,7 @@
 
 // Test expired certificates are not rejected.
 TEST_P(SSLStreamAdapterTestDTLS, TestCertExpired) {
+  MAYBE_SKIP_TEST(HaveDtls);
   long one_day = 60 * 60 * 24;
   // Make the certificates already expired.
   ResetIdentitiesWithValidity(-one_day, -one_day);
@@ -1215,12 +1240,15 @@
 
 // Test data transfer using certs created from strings.
 TEST_F(SSLStreamAdapterTestDTLSFromPEMStrings, TestTransfer) {
+  MAYBE_SKIP_TEST(HaveDtls);
   TestHandshake();
   TestTransfer(100);
 }
 
 // Test getting the remote certificate.
 TEST_F(SSLStreamAdapterTestDTLSFromPEMStrings, TestDTLSGetPeerCertificate) {
+  MAYBE_SKIP_TEST(HaveDtls);
+
   // Peer certificates haven't been received yet.
   ASSERT_FALSE(GetPeerCertificate(true));
   ASSERT_FALSE(GetPeerCertificate(false));
@@ -1254,6 +1282,7 @@
 // Test getting the used DTLS ciphers.
 // DTLS 1.2 enabled for neither client nor server -> DTLS 1.0 will be used.
 TEST_P(SSLStreamAdapterTestDTLS, TestGetSslCipherSuite) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetupProtocolVersions(rtc::SSL_PROTOCOL_DTLS_10, rtc::SSL_PROTOCOL_DTLS_10);
   TestHandshake();
 
@@ -1273,6 +1302,7 @@
 // Test getting the used DTLS 1.2 ciphers.
 // DTLS 1.2 enabled for client and server -> DTLS 1.2 will be used.
 TEST_P(SSLStreamAdapterTestDTLS, TestGetSslCipherSuiteDtls12Both) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetupProtocolVersions(rtc::SSL_PROTOCOL_DTLS_12, rtc::SSL_PROTOCOL_DTLS_12);
   TestHandshake();
 
@@ -1291,6 +1321,7 @@
 
 // DTLS 1.2 enabled for client only -> DTLS 1.0 will be used.
 TEST_P(SSLStreamAdapterTestDTLS, TestGetSslCipherSuiteDtls12Client) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetupProtocolVersions(rtc::SSL_PROTOCOL_DTLS_10, rtc::SSL_PROTOCOL_DTLS_12);
   TestHandshake();
 
@@ -1309,6 +1340,7 @@
 
 // DTLS 1.2 enabled for server only -> DTLS 1.0 will be used.
 TEST_P(SSLStreamAdapterTestDTLS, TestGetSslCipherSuiteDtls12Server) {
+  MAYBE_SKIP_TEST(HaveDtls);
   SetupProtocolVersions(rtc::SSL_PROTOCOL_DTLS_12, rtc::SSL_PROTOCOL_DTLS_10);
   TestHandshake();