media: Support better decoder switching

media/base/mock_filters.h

Index: media/base/mock_filters.h
diff --git a/media/base/mock_filters.h b/media/base/mock_filters.h
index 96f07a5b5466b2a282e050fe7c915de7fc9cc37e..f5f13360ed1017676c32538789c50534253f393a 100644
--- a/media/base/mock_filters.h
+++ b/media/base/mock_filters.h
@@ -179,7 +179,7 @@ class MockDemuxerStream : public DemuxerStream {
 
 class MockVideoDecoder : public VideoDecoder {
  public:
-  MockVideoDecoder();
+  explicit MockVideoDecoder(const std::string& decoder_name = "");

[watk, 2017/05/04 21:35:32]

You can default the name to "MockVideoDecoder" here instead of in
GetDisplayName()?

   virtual ~MockVideoDecoder();
 
   // VideoDecoder implementation.
@@ -197,12 +197,13 @@ class MockVideoDecoder : public VideoDecoder {
   MOCK_CONST_METHOD0(CanReadWithoutStalling, bool());
 
  private:
+  std::string decoder_name_;
   DISALLOW_COPY_AND_ASSIGN(MockVideoDecoder);
 };
 
 class MockAudioDecoder : public AudioDecoder {
  public:
-  MockAudioDecoder();
+  explicit MockAudioDecoder(const std::string& decoder_name = "");
   virtual ~MockAudioDecoder();
 
   // AudioDecoder implementation.
@@ -218,6 +219,7 @@ class MockAudioDecoder : public AudioDecoder {
   MOCK_METHOD1(Reset, void(const base::Closure&));
 
  private:
+  std::string decoder_name_;
   DISALLOW_COPY_AND_ASSIGN(MockAudioDecoder);
 };