Preliminary work for unprefixed MSE SourceBuffer.mode manipulation

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 4c08f27d9534a53f88bd14b99e547062ce90292f..097f9b5438951d589ef1da3acb296b0c5d1c8a80 100644
--- a/Source/modules/mediasource/SourceBuffer.cpp
+++ b/Source/modules/mediasource/SourceBuffer.cpp
@@ -65,6 +65,7 @@ SourceBuffer::SourceBuffer(PassOwnPtr<WebSourceBuffer> webSourceBuffer, MediaSou
     , m_webSourceBuffer(webSourceBuffer)
     , m_source(source)
     , m_asyncEventQueue(asyncEventQueue)
+    , m_mode(segmentsKeyword())
     , m_updating(false)
     , m_timestampOffset(0)
     , m_appendWindowStart(0)
@@ -89,6 +90,57 @@ SourceBuffer::~SourceBuffer()
     ASSERT(!m_stream);
 }
 
+const AtomicString& SourceBuffer::segmentsKeyword()
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, segments, ("segments", AtomicString::ConstructFromLiteral));
+    return segments;
+}
+
+const AtomicString& SourceBuffer::sequenceKeyword()
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, sequence, ("sequence", AtomicString::ConstructFromLiteral));
+    return sequence;
+}
+
+void SourceBuffer::setMode(const AtomicString& newMode, ExceptionState& exceptionState)
+{
+    // Section 3.1 On setting mode attribute steps.
+    // 1. Let new mode equal the new value being assigned to this attribute.
+    // 2. If new mode does not equal "segments" or "sequence", then throw an INVALID_ACCESS_ERR exception and abort
+    //    these steps.
+    if (newMode != segmentsKeyword() && newMode != sequenceKeyword()) {
+        exceptionState.throwUninformativeAndGenericDOMException(InvalidAccessError);
+        return;
+    }
+
+    // 3. If this object has been removed from the sourceBuffers attribute of the parent media source, then throw
+    //    an INVALID_STATE_ERR exception and abort these steps.
+    // 4. If the updating attribute equals true, then throw an INVALID_STATE_ERR exception and abort these steps.
+    if (isRemoved() || m_updating) {
+        exceptionState.throwUninformativeAndGenericDOMException(InvalidStateError);
+        return;
+    }
+
+    // 5. If the readyState attribute of the parent media source is in the "ended" state then run the following steps:
+    // 5.1 Set the readyState attribute of the parent media source to "open"
+    // 5.2 Queue a task to fire a simple event named sourceopen at the parent media source.
+    m_source->openIfInEndedState();
+
+    // 6. If the append state equals PARSING_MEDIA_SEGMENT, then throw an INVALID_STATE_ERR and abort these steps.
+    // 7. If the new mode equals "sequence", then set the group start timestamp to the highest presentation end timestamp.
+    // FIXME: Remove default no-op implementation once these steps are landed in Chromium. See http://crbug.com/249422.

[acolwell GONE FROM CHROMIUM, 2014/01/10 22:09:34]

nit: Remove this comment since nothing needs to change here when the Chromium
changes actually land.

[wolenetz, 2014/01/10 23:06:50]

Done.

+    WebSourceBuffer::AppendMode appendMode = WebSourceBuffer::AppendModeSegments;
+    if (newMode == sequenceKeyword())
+        appendMode = WebSourceBuffer::AppendModeSequence;
+    if (!m_webSourceBuffer->setMode(appendMode)) {
+        exceptionState.throwUninformativeAndGenericDOMException(InvalidStateError);
+        return;
+    }
+
+    // 8. Update the attribute to new mode.
+    m_mode = newMode;
+}
+
 PassRefPtr<TimeRanges> SourceBuffer::buffered(ExceptionState& exceptionState) const
 {
     // Section 3.1 buffered attribute steps.
@@ -128,7 +180,7 @@ void SourceBuffer::setTimestampOffset(double offset, ExceptionState& exceptionSt
     // 5. If this object is waiting for the end of a media segment to be appended, then throw an InvalidStateError
     // and abort these steps.
     //
-    // FIXME: Add step 6 text when mode attribute is implemented.
+    // FIXME: Add step 6 text when mode attribute is implemented. See http://crbug.com/249422.

[acolwell GONE FROM CHROMIUM, 2014/01/10 22:09:34]

nit: Might as well just add the step 6 text now since this will happen at the
Chromium level. I think you should file a bug for implementing this step in
WebSourceBufferImpl or SourceState and then put a comment referencing the bug in
the relevant place.

[wolenetz, 2014/01/10 23:06:50]

Done, including updating step 5's text to current spec. I filed
http://crbug.com/333437 and added a reference to it from a SourceState comment
introduced in patch set 2 of the initial Chromium side plumbing for SourceBuffer
mode setting (https://codereview.chromium.org/134883002/).

     if (!m_webSourceBuffer->setTimestampOffset(offset)) {
         exceptionState.throwUninformativeAndGenericDOMException(InvalidStateError);
         return;