Revert of Loosening the coupling between WebRTC and //third_party/protobuf (patchset #16 id:300001 of https://codereview.webrtc.org/2747863003/ )

Reason for revert:
I will try to reland next week because it is causing some problems.

Original issue's description:
> To accommodate some downstream WebRTC users we need to loosen
> the coupling between our code and the //third_party/protobuf.
>
> This includes using typedefs to define strings instead of
> assuming std::string.
>
> After this refactoring it will be possible to link with other
> protobuf implementations than the current one.
>
> We moved the PRESUBMIT check to another CL [1]. The goal of this
> presubmit is to avoid the direct usage of google::protobuf outside
> of the webrtc/base/protobuf_utils.h header file.
>
> [1] - https://codereview.webrtc.org/2753823003/
>
> BUG=webrtc:7340
> NOTRY=True
>
> Review-Url: https://codereview.webrtc.org/2747863003
> Cr-Commit-Position: refs/heads/master@{#17466}
> Committed: https://chromium.googlesource.com/external/webrtc/+/16ab93b952f9e8268f2e663ffe49548e8043d5af

TBR=kjellander@webrtc.org,henrik.lundin@webrtc.org,kwiberg@webrtc.org,michaelt@webrtc.org,peah@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7340

Review-Url: https://codereview.webrtc.org/2786363002
Cr-Commit-Position: refs/heads/master@{#17483}
diff --git a/webrtc/modules/audio_processing/BUILD.gn b/webrtc/modules/audio_processing/BUILD.gn
index 84545dd..36f5575 100644
--- a/webrtc/modules/audio_processing/BUILD.gn
+++ b/webrtc/modules/audio_processing/BUILD.gn
@@ -232,7 +232,6 @@
     "../..:webrtc_common",
     "../../audio/utility:audio_frame_operations",
     "../../base:gtest_prod",
-    "../../base:protobuf_utils",
     "../audio_coding:isac",
   ]
   public_deps = [
@@ -525,7 +524,6 @@
       ":audioproc_test_utils",
       "../..:webrtc_common",
       "../../base:gtest_prod",
-      "../../base:protobuf_utils",
       "../../base:rtc_base",
       "../../base:rtc_base_approved",
       "../../common_audio:common_audio",
@@ -658,10 +656,8 @@
     deps = [
       ":audio_processing",
       ":audioproc_test_utils",
-      "../../base:protobuf_utils",
       "//testing/gtest",
     ]
-
     if (rtc_enable_intelligibility_enhancer) {
       defines = [ "WEBRTC_INTELLIGIBILITY_ENHANCER=1" ]
     } else {
@@ -682,7 +678,6 @@
         ":audioproc_protobuf_utils",
         ":audioproc_test_utils",
         "../..:webrtc_common",
-        "../../base:protobuf_utils",
         "../../base:rtc_base_approved",
         "../../common_audio",
         "../../system_wrappers:system_wrappers_default",
@@ -707,7 +702,6 @@
         ":audioproc_debug_proto",
         ":audioproc_protobuf_utils",
         ":audioproc_test_utils",
-        "../../base:protobuf_utils",
         "../../base:rtc_base_approved",
         "../../common_audio:common_audio",
         "../../system_wrappers",
@@ -823,7 +817,6 @@
       deps = [
         ":audioproc_debug_proto",
         "../..:webrtc_common",
-        "../../base:protobuf_utils",
         "../../base:rtc_base_approved",
       ]
     }
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index 56da282..1f73c59 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -1879,11 +1879,11 @@
   audioproc::Init* msg = debug_dump_.capture.event_msg->mutable_init();
   msg->set_sample_rate(formats_.api_format.input_stream().sample_rate_hz());
 
-  msg->set_num_input_channels(static_cast<int32_t>(
+  msg->set_num_input_channels(static_cast<google::protobuf::int32>(
       formats_.api_format.input_stream().num_channels()));
-  msg->set_num_output_channels(static_cast<int32_t>(
+  msg->set_num_output_channels(static_cast<google::protobuf::int32>(
       formats_.api_format.output_stream().num_channels()));
-  msg->set_num_reverse_channels(static_cast<int32_t>(
+  msg->set_num_reverse_channels(static_cast<google::protobuf::int32>(
       formats_.api_format.reverse_input_stream().num_channels()));
   msg->set_reverse_sample_rate(
       formats_.api_format.reverse_input_stream().sample_rate_hz());
@@ -1953,7 +1953,7 @@
   }
   config.set_experiments_description(experiments_description);
 
-  ProtoString serialized_config = config.SerializeAsString();
+  std::string serialized_config = config.SerializeAsString();
   if (!forced &&
       debug_dump_.capture.last_serialized_config == serialized_config) {
     return kNoError;
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.h b/webrtc/modules/audio_processing/audio_processing_impl.h
index 2b6e6f6..01b640f 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.h
+++ b/webrtc/modules/audio_processing/audio_processing_impl.h
@@ -13,13 +13,13 @@
 
 #include <list>
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/function_view.h"
 #include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/ignore_wundef.h"
-#include "webrtc/base/protobuf_utils.h"
 #include "webrtc/base/swap_queue.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/modules/audio_processing/audio_buffer.h"
@@ -29,7 +29,7 @@
 #include "webrtc/system_wrappers/include/file_wrapper.h"
 
 #ifdef WEBRTC_AUDIOPROC_DEBUG_DUMP
-// *.pb.h files are generated at build-time by the protobuf compiler.
+// Files generated at build-time by the protobuf compiler.
 RTC_PUSH_IGNORING_WUNDEF()
 #ifdef WEBRTC_ANDROID_PLATFORM_BUILD
 #include "external/webrtc/webrtc/modules/audio_processing/debug.pb.h"
@@ -200,10 +200,10 @@
     ApmDebugDumpThreadState();
     ~ApmDebugDumpThreadState();
     std::unique_ptr<audioproc::Event> event_msg;  // Protobuf message.
-    ProtoString event_str;  // Memory for protobuf serialization.
+    std::string event_str;  // Memory for protobuf serialization.
 
     // Serialized string of last saved APM configuration.
-    ProtoString last_serialized_config;
+    std::string last_serialized_config;
   };
 
   struct ApmDebugDumpState {
diff --git a/webrtc/modules/audio_processing/audio_processing_unittest.cc b/webrtc/modules/audio_processing/audio_processing_unittest.cc
index 814eea9..b52acce 100644
--- a/webrtc/modules/audio_processing/audio_processing_unittest.cc
+++ b/webrtc/modules/audio_processing/audio_processing_unittest.cc
@@ -20,7 +20,6 @@
 #include "webrtc/base/checks.h"
 #include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/ignore_wundef.h"
-#include "webrtc/base/protobuf_utils.h"
 #include "webrtc/common_audio/include/audio_util.h"
 #include "webrtc/common_audio/resampler/include/push_resampler.h"
 #include "webrtc/common_audio/resampler/push_sinc_resampler.h"
@@ -59,7 +58,7 @@
 // file. This is the typical case. When the file should be updated, it can
 // be set to true with the command-line switch --write_ref_data.
 bool write_ref_data = false;
-const int32_t kChannels[] = {1, 2};
+const google::protobuf::int32 kChannels[] = {1, 2};
 const int kSampleRates[] = {8000, 16000, 32000, 48000};
 
 #if defined(WEBRTC_AUDIOPROC_FIXED_PROFILE)
@@ -231,7 +230,7 @@
 #endif
 
 void OpenFileAndWriteMessage(const std::string filename,
-                             const MessageLite& msg) {
+                             const ::google::protobuf::MessageLite& msg) {
   FILE* file = fopen(filename.c_str(), "wb");
   ASSERT_TRUE(file != NULL);
 
@@ -300,7 +299,8 @@
     remove(kv.second.c_str());
 }
 
-void OpenFileAndReadMessage(std::string filename, MessageLite* msg) {
+void OpenFileAndReadMessage(std::string filename,
+                            ::google::protobuf::MessageLite* msg) {
   FILE* file = fopen(filename.c_str(), "rb");
   ASSERT_TRUE(file != NULL);
   ReadMessageFromFile(file, msg);
diff --git a/webrtc/modules/audio_processing/test/protobuf_utils.cc b/webrtc/modules/audio_processing/test/protobuf_utils.cc
index cb8adf9..c18a13e 100644
--- a/webrtc/modules/audio_processing/test/protobuf_utils.cc
+++ b/webrtc/modules/audio_processing/test/protobuf_utils.cc
@@ -30,7 +30,7 @@
 }
 
 // Returns true on success, false on error or end-of-file.
-bool ReadMessageFromFile(FILE* file, MessageLite* msg) {
+bool ReadMessageFromFile(FILE* file, ::google::protobuf::MessageLite* msg) {
   std::unique_ptr<uint8_t[]> bytes;
   size_t size = ReadMessageBytesFromFile(file, &bytes);
   if (!size)
diff --git a/webrtc/modules/audio_processing/test/protobuf_utils.h b/webrtc/modules/audio_processing/test/protobuf_utils.h
index 8941338..e132c94 100644
--- a/webrtc/modules/audio_processing/test/protobuf_utils.h
+++ b/webrtc/modules/audio_processing/test/protobuf_utils.h
@@ -14,7 +14,6 @@
 #include <memory>
 
 #include "webrtc/base/ignore_wundef.h"
-#include "webrtc/base/protobuf_utils.h"
 
 RTC_PUSH_IGNORING_WUNDEF()
 #include "webrtc/modules/audio_processing/debug.pb.h"
@@ -27,7 +26,7 @@
 size_t ReadMessageBytesFromFile(FILE* file, std::unique_ptr<uint8_t[]>* bytes);
 
 // Returns true on success, false on error or end-of-file.
-bool ReadMessageFromFile(FILE* file, MessageLite* msg);
+bool ReadMessageFromFile(FILE* file, ::google::protobuf::MessageLite* msg);
 
 }  // namespace webrtc