media: Remove SetCdmReadyCB and CdmReadyCB (part 1).

media/base/test_helpers.h

Index: media/base/test_helpers.h
diff --git a/media/base/test_helpers.h b/media/base/test_helpers.h
index 214526439f3289116c43c8bc67af8c257d3d3c8a..8576aa8939c1d93ccdcfa51014f1b530442c40b6 100644
--- a/media/base/test_helpers.h
+++ b/media/base/test_helpers.h
@@ -133,19 +133,6 @@ scoped_refptr<DecoderBuffer> CreateFakeVideoBufferForTest(
 bool VerifyFakeVideoBufferForTest(const scoped_refptr<DecoderBuffer>& buffer,
                                   const VideoDecoderConfig& config);
 
-// Used to verify that the each call to A() is followed by a call to B(),
-// before the next call to A(). There may be any number of pairs (including 0).
-class CallbackPairChecker {
- public:
-  CallbackPairChecker();
-  ~CallbackPairChecker();
-  void RecordACalled();
-  void RecordBCalled();
-
- private:
-  bool expecting_b_;
-};
-
 }  // namespace media
 
 #endif  // MEDIA_BASE_TEST_HELPERS_H_