VideoAdapter: Drop frames based on actual fps instead of expected fps

webrtc/media/base/videoadapter.h

Index: webrtc/media/base/videoadapter.h
diff --git a/webrtc/media/base/videoadapter.h b/webrtc/media/base/videoadapter.h
index 2db0ada271324f5b61350ef0ca508d4d8856fdbe..45fd1fa8274ef3b85adfbb98cd3c8c598cfdf7d5 100644
--- a/webrtc/media/base/videoadapter.h
+++ b/webrtc/media/base/videoadapter.h
@@ -27,17 +27,13 @@ class VideoAdapter {
   VideoAdapter();
   virtual ~VideoAdapter();
 
-  // Sets the expected frame interval. This controls how often frames should
-  // be dropped if |OnOutputFormatRequest| is called with a lower frame
-  // interval.
-  void SetExpectedInputFrameInterval(int64_t interval);
-
   // Return the adapted resolution given the input resolution. The input
   // resolution should first be cropped to the specified resolution, and then
   // scaled to the final output resolution. The output resolution will be 0x0 if
   // the frame should be dropped.
   void AdaptFrameResolution(int in_width,
                             int in_height,
+                            int64_t in_timestamp_ns,
                             int* cropped_width,
                             int* cropped_height,
                             int* out_width,
@@ -58,14 +54,17 @@ class VideoAdapter {
                            rtc::Optional<int> max_pixel_count_step_up);
 
  private:
+  // Determine if frame should be dropped based on input fps and requested fps.
+  bool KeepFrame(int64_t in_timestamp_ns);
+
   int frames_in_;         // Number of input frames.
   int frames_out_;        // Number of output frames.
   int frames_scaled_;     // Number of frames scaled.
   int adaption_changes_;  // Number of changes in scale factor.
   int previous_width_;    // Previous adapter output width.
   int previous_height_;   // Previous adapter output height.
-  int input_interval_ GUARDED_BY(critical_section_);
-  int64_t interval_next_frame_ GUARDED_BY(critical_section_);
+  // The target timestamp for the next frame based on requested format.
+  rtc::Optional<int64_t> next_frame_timestamp_ns_ GUARDED_BY(critical_section_);
 
   // Max number of pixels requested via calls to OnOutputFormatRequest,
   // OnResolutionRequest respectively.