The AudioProcessing class is used as an interface

to the functionality in the audio processing module.
Therefore, it should be a pure interface.
This CL ensures that is the case.

BUG=webrtc:6515

Review-Url: https://codereview.webrtc.org/2406193002
Cr-Commit-Position: refs/heads/master@{#14608}

webrtc/modules/audio_processing/include/mock_audio_processing.h

@@ -259,6 +259,10 @@ class MockAudioProcessing : public AudioProcessing {
                    int64_t max_log_size_bytes));
   MOCK_METHOD2(StartDebugRecording,
                int(FILE* handle, int64_t max_log_size_bytes));
+  MOCK_METHOD1(StartDebugRecording,
+               int (FILE* handle));
+  MOCK_METHOD1(StartDebugRecording,
+               int(rtc::PlatformFile handle));
   MOCK_METHOD0(StopDebugRecording,
       int());
   MOCK_METHOD0(UpdateHistogramsOnCallEnd, void());