MSE: Start letting SourceBuffer begin to do initialization segment received algorithm

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 b96ae089ced46efedc12fce4dde6d8cac5e3b674..632abf9e876bb64218d2eaadea829f5952cde75c 100644
--- a/Source/modules/mediasource/SourceBuffer.cpp
+++ b/Source/modules/mediasource/SourceBuffer.cpp
@@ -89,6 +89,7 @@ SourceBuffer::SourceBuffer(PassOwnPtr<WebSourceBuffer> webSourceBuffer, MediaSou
     , m_timestampOffset(0)
     , m_appendWindowStart(0)
     , m_appendWindowEnd(std::numeric_limits<double>::infinity())
+    , m_firstInitializationSegmentReceived(false)
     , m_pendingAppendDataOffset(0)
     , m_appendBufferAsyncPartRunner(this, &SourceBuffer::appendBufferAsyncPart)
     , m_pendingRemoveStart(-1)
@@ -101,6 +102,7 @@ SourceBuffer::SourceBuffer(PassOwnPtr<WebSourceBuffer> webSourceBuffer, MediaSou
     ASSERT(m_webSourceBuffer);
     ASSERT(m_source);
     ScriptWrappable::init(this);
+    m_webSourceBuffer->setClient(this);
 }
 
 SourceBuffer::~SourceBuffer()
@@ -112,6 +114,7 @@ SourceBuffer::~SourceBuffer()
     ASSERT(isRemoved());
     ASSERT(!m_loader);
     ASSERT(!m_stream);
+    ASSERT(!m_webSourceBuffer);

[philipj_slow, 2014/09/11 13:38:32]

Is this a drive-by fix, or did something change so that this assert now holds
true? I don't see it.

[wolenetz, 2014/09/11 21:41:17]

This is a drive-by for added clarification of |m_webSourceBuffer|'s non-null
lifetime. If isRemoved() assertion fails, above, this assertion will also fail
with current code, since removedFromMediaSource() clears both. I'm fine with
removing this line if you wish.

[philipj_slow, 2014/09/12 08:45:28]

A little drive-by fixing is fine, just wanted to understand :)

 #endif
 }
 
@@ -420,6 +423,29 @@ void SourceBuffer::removedFromMediaSource()
     m_asyncEventQueue = 0;
 }
 
+void SourceBuffer::initializationSegmentReceived()
+{
+    ASSERT(m_source);
+    ASSERT(m_updating);
+
+    // https://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html#sourcebuffer-init-segment-received
+    // FIXME: Make steps 1-7 synchronous with this call.

[philipj_slow, 2014/09/11 13:38:32]

Yeah, that algorithm does a lot that's apparently done elsewhere, or not at all
:)

[wolenetz, 2014/09/11 21:41:17]

I'll be working on subsequent CLs that improve compliance around this. Chromium
currently hops threads to set duration and transition to HAVE_METADATA as a
result of receiving init segment(s). Both, along with adding the necessary
tracks, would best be done here now that it's plumbed into Blink. |m_source|
knows the element it's attached to, so I can remove those Chromium thread hops
(and centralize in a maintainable, readable location the core of the
initSegmentReceived algorithm.)

[philipj_slow, 2014/09/12 08:45:28]

Looking forward to those changes!

+    // FIXME: Augment the interface to this method to implement compliant steps 4-7 here.
+    // Step 3 (if the first initialization segment received flag is true) is
+    // implemented by caller.
+
+    if (!m_firstInitializationSegmentReceived) {
+        // 5. If active track flag equals true, then run the following steps:
+        // 5.1. Add this SourceBuffer to activeSourceBuffers.
+        // 5.2. Queue a task to fire a simple event named addsourcebuffer at
+        // activesourcebuffers.
+        m_source->setSourceBufferActive(this);
+
+        // 6. Set first initialization segment received flag to true.
+        m_firstInitializationSegmentReceived = true;
+    }
+}
+
 bool SourceBuffer::hasPendingActivity() const
 {
     return m_source;