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}
diff --git a/webrtc/modules/audio_processing/test/protobuf_utils.h b/webrtc/modules/audio_processing/test/protobuf_utils.h
index e132c94..8941338 100644
--- a/webrtc/modules/audio_processing/test/protobuf_utils.h
+++ b/webrtc/modules/audio_processing/test/protobuf_utils.h
@@ -14,6 +14,7 @@
 #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"
@@ -26,7 +27,7 @@
 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, ::google::protobuf::MessageLite* msg);
+bool ReadMessageFromFile(FILE* file, MessageLite* msg);
 
 }  // namespace webrtc