Implement evictFrames() to support MSE's coded frame eviction algorithm.

media/filters/source_buffer_range.h

Index: media/filters/source_buffer_range.h
diff --git a/media/filters/source_buffer_range.h b/media/filters/source_buffer_range.h
index 24f88fb10ac286e233f644041a731aeb76774d97..71277d5e1104a8c7e0e398836b8f5c77f8a3b732 100644
--- a/media/filters/source_buffer_range.h
+++ b/media/filters/source_buffer_range.h
@@ -124,6 +124,8 @@ class SourceBufferRange {
       DecodeTimestamp start_timestamp, DecodeTimestamp end_timestamp,
       int bytes_to_free, DecodeTimestamp* end_removal_timestamp);
 
+  bool FirstGOPEarlierThanMediaTime(DecodeTimestamp media_time) const;
+
   // Indicates whether the GOP at the beginning or end of the range contains the
   // next buffer position.
   bool FirstGOPContainsNextBufferPosition() const;