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

Provided interface in ChunkDemuxer/WebSourceBuffer to allow blink to
invoke "3.5.12 Coded Frame Eviction Algorithm"
https://w3c.github.io/media-source/#sourcebuffer-coded-frame-eviction

This allows us to detect when buffer is full, even after GC
and throw QuotaExceededErr exception as MSE spec prescribes.
See step #6 in section 3.5.4 at
https://w3c.github.io/media-source/#sourcebuffer-prepare-append
Related Chromium CL: https://codereview.chromium.org/1008463002/

BUG=421694

Review URL: https://codereview.chromium.org/1013923002

git-svn-id: svn://svn.chromium.org/blink/trunk@200989 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/modules/mediasource/MediaSource.cpp

@@ -156,6 +156,7 @@ SourceBuffer* MediaSource::addSourceBuffer(const String& type, ExceptionState& e
     m_sourceBuffers->add(buffer);
 
     // 7. Return the new object to the caller.
+    WTF_LOG(Media, "MediaSource::addSourceBuffer(%s) %p -> %p", type.ascii().data(), this, buffer);
     return buffer;
 }
 
@@ -515,6 +516,11 @@ void MediaSource::setSourceBufferActive(SourceBuffer* sourceBuffer)
     m_activeSourceBuffers->insert(insertPosition, sourceBuffer);
 }
 
+HTMLMediaElement* MediaSource::mediaElement() const
+{
+    return m_attachedElement.get();
+}
+
 bool MediaSource::isClosed() const
 {
     return readyState() == closedKeyword();

third_party/WebKit/Source/modules/mediasource/MediaSource.h

@@ -101,6 +101,7 @@ public:
     void openIfInEndedState();
     bool isOpen() const;
     void setSourceBufferActive(SourceBuffer*);
+    HTMLMediaElement* mediaElement() const;
 
     // Used by MediaSourceRegistry.
     void addedToRegistry();

third_party/WebKit/Source/modules/mediasource/SourceBuffer.h

@@ -114,8 +114,11 @@ private:
     bool isRemoved() const;
     void scheduleEvent(const AtomicString& eventName);
 
+    bool prepareAppend(size_t newDataSize, ExceptionState&);
+    bool evictCodedFrames(size_t newDataSize);
     void appendBufferInternal(const unsigned char*, unsigned, ExceptionState&);
     void appendBufferAsyncPart();
+    void appendError(bool decodeError);
 
     void removeAsyncPart();
 

third_party/WebKit/public/platform/WebSourceBuffer.h

@@ -53,6 +53,14 @@ public:
     virtual bool setMode(AppendMode) = 0;
     virtual WebTimeRanges buffered() = 0;
 
+    // Run coded frame eviction/garbage collection algorithm.
+    // |currentPlaybackTime| is HTMLMediaElement::currentTime. The algorithm
+    // will try to preserve data around current playback position.
+    // |newDataSize| is size of new data about to be appended to SourceBuffer.
+    // Could be zero for appendStream if stream size is unknown in advance.
+    // Returns false if buffer is still full after eviction.
+    virtual bool evictCodedFrames(double currentPlaybackTime, size_t newDataSize) = 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;