Move webrtc/{base => rtc_base}

This refactoring takes a careful approach to avoid rushing the change:
* stub headers are left in all the old locations of webrtc/base
* existing GN targets are kept and now just forward to the moved ones
  using public_deps.
The only exception to the above is the base_java target and its .java files,
which were moved to webrtc/rtc_base right away since it's not possible
to use public_deps for android_library.
To avoid breaking builds, a temporary Dummy.java file was added to
the new intermediate target in webrtc/rtc_base:base_java as well to avoid
hitting a GN assert in the android_library template.

The above approach should make the transition smooth without breaking
downstream.

A helper script was created (https://codereview.webrtc.org/2879203002/)
and was run like this:
stub-headers.py -s webrtc/base -d webrtc/rtc_base -i 7634
stub-headers.py -s webrtc/base/numerics -d webrtc/rtc_base/numerics -i 7634

Fixed invalid header guards in the following files:
webrtc/base/base64.h
webrtc/base/cryptstring.h
webrtc/base/event.h
webrtc/base/flags.h
webrtc/base/httpbase.h
webrtc/base/httpcommon-inl.h
webrtc/base/httpcommon.h
webrtc/base/httpserver.h
webrtc/base/logsinks.h
webrtc/base/macutils.h
webrtc/base/nattypes.h
webrtc/base/openssladapter.h
webrtc/base/opensslstreamadapter.h
webrtc/base/pathutils.h
webrtc/base/physicalsocketserver.h
webrtc/base/proxyinfo.h
webrtc/base/sigslot.h
webrtc/base/sigslotrepeater.h
webrtc/base/socket.h
webrtc/base/socketaddresspair.h
webrtc/base/socketfactory.h
webrtc/base/stringutils.h
webrtc/base/testbase64.h
webrtc/base/testutils.h
webrtc/base/transformadapter.h
webrtc/base/win32filesystem.h

Added new header guards to:
sslroots.h
testbase64.h

BUG=webrtc:7634
NOTRY=True
NOPRESUBMIT=True
R=kwiberg@webrtc.org

Review-Url: https://codereview.webrtc.org/2877023002 .
Cr-Commit-Position: refs/heads/master@{#18816}
diff --git a/webrtc/rtc_base/bytebuffer.h b/webrtc/rtc_base/bytebuffer.h
new file mode 100644
index 0000000..b631ae1
--- /dev/null
+++ b/webrtc/rtc_base/bytebuffer.h
@@ -0,0 +1,139 @@
+/*
+ *  Copyright 2004 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_RTC_BASE_BYTEBUFFER_H_
+#define WEBRTC_RTC_BASE_BYTEBUFFER_H_
+
+#include <string>
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/buffer.h"
+#include "webrtc/base/constructormagic.h"
+
+namespace rtc {
+
+class ByteBuffer {
+ public:
+  enum ByteOrder {
+    ORDER_NETWORK = 0,  // Default, use network byte order (big endian).
+    ORDER_HOST,         // Use the native order of the host.
+  };
+
+  explicit ByteBuffer(ByteOrder byte_order) : byte_order_(byte_order) {}
+
+  ByteOrder Order() const { return byte_order_; }
+
+ private:
+  ByteOrder byte_order_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(ByteBuffer);
+};
+
+class ByteBufferWriter : public ByteBuffer {
+ public:
+  // |byte_order| defines order of bytes in the buffer.
+  ByteBufferWriter();
+  explicit ByteBufferWriter(ByteOrder byte_order);
+  ByteBufferWriter(const char* bytes, size_t len);
+  ByteBufferWriter(const char* bytes, size_t len, ByteOrder byte_order);
+
+  ~ByteBufferWriter();
+
+  const char* Data() const { return bytes_; }
+  size_t Length() const { return end_; }
+  size_t Capacity() const { return size_; }
+
+  // Write value to the buffer. Resizes the buffer when it is
+  // neccessary.
+  void WriteUInt8(uint8_t val);
+  void WriteUInt16(uint16_t val);
+  void WriteUInt24(uint32_t val);
+  void WriteUInt32(uint32_t val);
+  void WriteUInt64(uint64_t val);
+  void WriteUVarint(uint64_t val);
+  void WriteString(const std::string& val);
+  void WriteBytes(const char* val, size_t len);
+
+  // Reserves the given number of bytes and returns a char* that can be written
+  // into. Useful for functions that require a char* buffer and not a
+  // ByteBufferWriter.
+  char* ReserveWriteBuffer(size_t len);
+
+  // Resize the buffer to the specified |size|.
+  void Resize(size_t size);
+
+  // Clears the contents of the buffer. After this, Length() will be 0.
+  void Clear();
+
+ private:
+  void Construct(const char* bytes, size_t size);
+
+  char* bytes_;
+  size_t size_;
+  size_t end_;
+
+  // There are sensible ways to define these, but they aren't needed in our code
+  // base.
+  RTC_DISALLOW_COPY_AND_ASSIGN(ByteBufferWriter);
+};
+
+// The ByteBufferReader references the passed data, i.e. the pointer must be
+// valid during the lifetime of the reader.
+class ByteBufferReader : public ByteBuffer {
+ public:
+  ByteBufferReader(const char* bytes, size_t len);
+  ByteBufferReader(const char* bytes, size_t len, ByteOrder byte_order);
+
+  // Initializes buffer from a zero-terminated string.
+  explicit ByteBufferReader(const char* bytes);
+
+  explicit ByteBufferReader(const Buffer& buf);
+
+  explicit ByteBufferReader(const ByteBufferWriter& buf);
+
+  // Returns start of unprocessed data.
+  const char* Data() const { return bytes_ + start_; }
+  // Returns number of unprocessed bytes.
+  size_t Length() const { return end_ - start_; }
+
+  // Read a next value from the buffer. Return false if there isn't
+  // enough data left for the specified type.
+  bool ReadUInt8(uint8_t* val);
+  bool ReadUInt16(uint16_t* val);
+  bool ReadUInt24(uint32_t* val);
+  bool ReadUInt32(uint32_t* val);
+  bool ReadUInt64(uint64_t* val);
+  bool ReadUVarint(uint64_t* val);
+  bool ReadBytes(char* val, size_t len);
+
+  // Appends next |len| bytes from the buffer to |val|. Returns false
+  // if there is less than |len| bytes left.
+  bool ReadString(std::string* val, size_t len);
+
+  // Moves current position |size| bytes forward. Returns false if
+  // there is less than |size| bytes left in the buffer. Consume doesn't
+  // permanently remove data, so remembered read positions are still valid
+  // after this call.
+  bool Consume(size_t size);
+
+ private:
+  void Construct(const char* bytes, size_t size);
+
+  const char* bytes_;
+  size_t size_;
+  size_t start_;
+  size_t end_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(ByteBufferReader);
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_RTC_BASE_BYTEBUFFER_H_