Delete unused class MockVCMFrameTypeCallback

Unused since https://codereview.webrtc.org/2755803004

Bug: None
Change-Id: I5c5180fa990235f6353dd972cf4cc05676730a3b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/132541
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27562}
diff --git a/modules/video_coding/include/mock/mock_vcm_callbacks.h b/modules/video_coding/include/mock/mock_vcm_callbacks.h
index e604cab..3749a6a 100644
--- a/modules/video_coding/include/mock/mock_vcm_callbacks.h
+++ b/modules/video_coding/include/mock/mock_vcm_callbacks.h
@@ -16,11 +16,6 @@
 
 namespace webrtc {
 
-class MockVCMFrameTypeCallback : public VCMFrameTypeCallback {
- public:
-  MOCK_METHOD0(RequestKeyFrame, int32_t());
-};
-
 class MockPacketRequestCallback : public VCMPacketRequestCallback {
  public:
   MOCK_METHOD2(ResendPackets,