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

Source/modules/mediasource/SourceBuffer.cpp

Index: Source/modules/mediasource/SourceBuffer.cpp
diff --git a/Source/modules/mediasource/SourceBuffer.cpp b/Source/modules/mediasource/SourceBuffer.cpp
index ceea5a8db2bc65ba31173ef4588b53b514fd3e84..0d1e128f4597b969abee68eeedfaa91384169476 100644
--- a/Source/modules/mediasource/SourceBuffer.cpp
+++ b/Source/modules/mediasource/SourceBuffer.cpp
@@ -530,7 +530,12 @@ void SourceBuffer::appendBufferInternal(const unsigned char* data, unsigned size
     //  3. If the readyState attribute of the parent media source is in the "ended" state then run the following steps: ...
     m_source->openIfInEndedState();
 
-    //  Steps 4-5 - end "prepare append" algorithm.
+    //  4. Run the coded frame eviction algorithm.
+    if (!evictCodedFrames()) {
+        //  5. If the buffer full flag equals true, then throw a QUOTA_EXCEEDED_ERR exception and abort these steps.
+        exceptionState.throwDOMException(QuotaExceededError, "The SourceBuffer is full, and cannot free space to append additional buffers.");
+        return;
+    }
 
     // 2. Add data to the end of the input buffer.
     ASSERT(data || size == 0);
@@ -628,6 +633,11 @@ void SourceBuffer::removeAsyncPart()
     scheduleEvent(EventTypeNames::updateend);
 }
 
+bool SourceBuffer::evictCodedFrames()
+{
+    return m_webSourceBuffer->evictCodedFrames();
+}
+
 void SourceBuffer::appendStreamInternal(Stream* stream, ExceptionState& exceptionState)
 {
     // Section 3.2 appendStream()
@@ -651,7 +661,12 @@ void SourceBuffer::appendStreamInternal(Stream* stream, ExceptionState& exceptio
     //  3. If the readyState attribute of the parent media source is in the "ended" state then run the following steps: ...
     m_source->openIfInEndedState();
 
-    // Steps 4-5 of the prepare append algorithm are handled by m_webSourceBuffer.
+    // 4. Run the coded frame eviction algorithm.
+    if (!evictCodedFrames()) {
+        //  5. If the buffer full flag equals true, then throw a QUOTA_EXCEEDED_ERR exception and abort these steps.
+        exceptionState.throwDOMException(QuotaExceededError, "The SourceBuffer is full, and cannot free space to append stream.");
+        return;
+    }
 
     // 2. Set the updating attribute to true.
     m_updating = true;
@@ -683,7 +698,7 @@ void SourceBuffer::appendStreamAsyncPart()
         return;
     }
 
-    // Steps 3-11 are handled by m_loader.
+    // Steps 3-9 are handled by m_loader.
     // Note: Passing 0 here signals that maxSize was not set. (i.e. Read all the data in the stream).
     m_loader->start(executionContext(), *m_stream, m_streamMaxSizeValid ? m_streamMaxSize : 0);
 }
@@ -697,24 +712,22 @@ void SourceBuffer::appendStreamDone(bool success)
     clearAppendStreamState();
 
     if (!success) {
-        // Section 3.5.3 Append Error Algorithm
-        // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#sourcebuffer-append-error
-        //
-        // 1. Run the reset parser state algorithm. (Handled by caller)
-        // 2. Set the updating attribute to false.
-        m_updating = false;
-
-        // 3. Queue a task to fire a simple event named error at this SourceBuffer object.
-        scheduleEvent(EventTypeNames::error);
-
-        // 4. Queue a task to fire a simple event named updateend at this SourceBuffer object.
-        scheduleEvent(EventTypeNames::updateend);
+        appendError(false);
         TRACE_EVENT_ASYNC_END0("media", "SourceBuffer::appendStream", this);
         return;
     }
 
     // Section 3.5.6 Stream Append Loop
-    // Steps 1-11 are handled by appendStreamAsyncPart(), |m_loader|, and |m_webSourceBuffer|.
+    // Steps 1-9 are handled by appendStreamAsyncPart(), |m_loader|, and |m_webSourceBuffer|.
+
+    // 10. Run the coded frame eviction algorithm.
+    if (!evictCodedFrames()) {
+        // 11. If the buffer full flag equals true, then run the append error algorithm with the decode error parameter set to false and abort this algorithm.
+        appendError(false);
+        TRACE_EVENT_ASYNC_END0("media", "SourceBuffer::appendStream", this);
+        return;
+    }
+
     // 12. Loop Done: Set the updating attribute to false.
     m_updating = false;
 
@@ -734,6 +747,29 @@ void SourceBuffer::clearAppendStreamState()
     m_stream = nullptr;
 }
 
+void SourceBuffer::appendError(bool decodeError)
+{
+    // Section 3.5.3 Append Error Algorithm
+    // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#sourcebuffer-append-error
+    //
+    // 1. Run the reset parser state algorithm. (Handled by caller)
+    // 2. Set the updating attribute to false.
+    m_updating = false;
+
+    // 3. Queue a task to fire a simple event named error at this SourceBuffer object.
+    scheduleEvent(EventTypeNames::error);
+
+    // 4. Queue a task to fire a simple event named updateend at this SourceBuffer object.
+    scheduleEvent(EventTypeNames::updateend);
+
+    // 5. If decode error is true, then run the end of stream algorithm with the
+    // error parameter set to "decode".
+    // TODO(servolk): endOfStream expects ExceptionState parameter, but it is

[philipj_slow, 2015/06/03 12:43:32]

The exception to worry about is the throwExceptionIfClosedOrUpdating(isOpen(),
isUpdating(), exceptionState) in MediaSource::endOfStreamInternal. We're
definitely not updating here and if it possible to be closed that would be a
spec problem, since there's nothing to do with the exception. If you poke around
a bit an conclude that the exception cannot occur here, just pass
ASSERT_NO_EXCEPTION for the ExceptionState&.

[servolk, 2015/06/18 23:23:28]

Done.

+    // unavailable here. Do we need to implement passing ExceptionState from
+    // somewhere or just instantiate it here?
+    // m_source->endOfStream("decode", ExceptionState?);
+}
+
 void SourceBuffer::didStartLoading()
 {
     WTF_LOG(Media, "SourceBuffer::didStartLoading() %p", this);