Fix MSE GC, make it less aggressive, more spec-compliant (Blink CL)

public/platform/WebSourceBuffer.h

Index: public/platform/WebSourceBuffer.h
diff --git a/public/platform/WebSourceBuffer.h b/public/platform/WebSourceBuffer.h
index 689504b47cf9dd0789cf73c360b571c32fe829ab..f5aee9bd8e6e3320669accd50f00c627b74ac51d 100644
--- a/public/platform/WebSourceBuffer.h
+++ b/public/platform/WebSourceBuffer.h
@@ -53,6 +53,10 @@ public:
     virtual bool setMode(AppendMode) = 0;
     virtual WebTimeRanges buffered() = 0;
 
+    // Evict frames for coded frame eviction algorithm.
+    // Returns false if buffer is still full after eviction.
+    virtual bool evictCodedFrames() = 0;
+
     // Appends data and runs the segment parser loop algorithm.
     // The algorithm may update |*timestampOffset| if |timestampOffset| is not null.
     virtual void append(const unsigned char* data, unsigned length, double* timestampOffset) = 0;