Enable round-tripping and updating of SourceBuffer timestamp offset

This is the second part of a three-sided MediaSource 
Chromium/Blink+roll Blink/Chromium set of changes to enable 
JavaScript web apps to continue to round-trip 
SourceBuffer.timestampOffset set/get if SourceBuffer append 
operations do not update the timestamp offset, and to 
retrieve any updated timestamp offset as can occur during 
upcoming "sequence" append mode compliant coded frame 
processing. 

R=acolwell@chromium.org,jamesr@chromium.org
BUG=249422
TEST=No local linux regressions of http/tests/media/media-source/ layout tests

Review URL: https://codereview.chromium.org/178763006

git-svn-id: svn://svn.chromium.org/blink/trunk@168163 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/http/tests/media/media-source/mediasource-sourcebuffer-mode.html

@@ -102,7 +102,8 @@
                   assert_equals(sourceBuffer.mode, 'segments');
                   sourceBuffer.mode = 'segments';  // No exception should occur.
                   assert_equals(sourceBuffer.timestampOffset, 0.0);
-                  sourceBuffer.timestampOffset = 10.0;  // No exception should occur.
+                  sourceBuffer.timestampOffset = 10.123456789;  // No exception should occur.
+                  assert_equals(sourceBuffer.timestampOffset, 10.123456789);  // Super-precise offsets should round-trip.
 
                   // Append first part of media segment.
                   test.expectEvent(sourceBuffer, 'updateend', 'Partial media segment append ended.');
@@ -116,7 +117,7 @@
                   assert_throws('InvalidStateError',
                       function() { sourceBuffer.mode = 'segments'; },
                       'Setting valid sourceBuffer.mode while still parsing media segment threw InvalidStateError.');
-                  assert_equals(sourceBuffer.timestampOffset, 10.0);
+                  assert_equals(sourceBuffer.timestampOffset, 10.123456789);
                   assert_throws('InvalidStateError',
                       function() { sourceBuffer.timestampOffset = 20.0; },
                       'Setting valid sourceBuffer.timestampOffset while still parsing media segment threw InvalidStateError.');
@@ -131,7 +132,7 @@
                   assert_false(sourceBuffer.updating, 'updating attribute is false');
                   assert_equals(sourceBuffer.mode, 'segments');
                   sourceBuffer.mode = 'segments';  // No exception should occur.
-                  assert_equals(sourceBuffer.timestampOffset, 10.0);
+                  assert_equals(sourceBuffer.timestampOffset, 10.123456789);
                   sourceBuffer.timestampOffset = 20.0;  // No exception should occur.
                   test.done();
               });

third_party/WebKit/LayoutTests/http/tests/media/media-source/webkitmediasource-objects-expected.txt

@@ -37,6 +37,11 @@ EXPECTED (mediaSource.sourceBuffers[0].buffered.length == '2') OK
 EXPECTED (mediaSource.sourceBuffers[0].buffered.start(1) == '5') OK
 EXPECTED (mediaSource.sourceBuffers[0].buffered.end(1) > '5') OK
 
+Round-trip a precise timestampOffset
+EXPECTED (segmentHelper.sourceBuffer.timestampOffset == '5') OK
+RUN(segmentHelper.sourceBuffer.timestampOffset = 5.123456789)
+EXPECTED (segmentHelper.sourceBuffer.timestampOffset == '5.123456789') OK
+
 Remove SourceBuffer
 RUN(mediaSource.removeSourceBuffer(segmentHelper.sourceBuffer))
 EXPECTED (mediaSource.sourceBuffers.length == '0') OK

third_party/WebKit/LayoutTests/http/tests/media/media-source/webkitmediasource-objects.html

@@ -61,6 +61,13 @@
                 testExpected("mediaSource.sourceBuffers[0].buffered.start(1)", 5);
                 testExpected("mediaSource.sourceBuffers[0].buffered.end(1)", 5, '>');
 
+                // Confirm that sub-microsecond granularity timestamps round-trip set/get.
+                consoleWrite("");
+                consoleWrite("Round-trip a precise timestampOffset");
+                testExpected("segmentHelper.sourceBuffer.timestampOffset", 5);
+                run("segmentHelper.sourceBuffer.timestampOffset = 5.123456789");
+                testExpected("segmentHelper.sourceBuffer.timestampOffset", 5.123456789);
+
                 consoleWrite("");
                 consoleWrite("Remove SourceBuffer");
 

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

@@ -534,7 +534,7 @@ void SourceBuffer::appendBufferAsyncPart()
         // so that it can clear its end of stream state if necessary.
         m_pendingAppendData.resize(1);
     }
-    m_webSourceBuffer->append(m_pendingAppendData.data(), appendSize);
+    m_webSourceBuffer->append(m_pendingAppendData.data(), appendSize, &m_timestampOffset);
 
     // 3. Set the updating attribute to false.
     m_updating = false;
@@ -688,8 +688,7 @@ void SourceBuffer::didReceiveDataForClient(const char* data, unsigned dataLength
     WTF_LOG(Media, "SourceBuffer::didReceiveDataForClient(%d) %p", dataLength, this);
     ASSERT(m_updating);
     ASSERT(m_loader);
-
-    m_webSourceBuffer->append(reinterpret_cast<const unsigned char*>(data), dataLength);
+    m_webSourceBuffer->append(reinterpret_cast<const unsigned char*>(data), dataLength, &m_timestampOffset);
 }
 
 void SourceBuffer::didFinishLoading()

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

@@ -136,7 +136,10 @@ void WebKitSourceBuffer::append(PassRefPtr<Uint8Array> data, ExceptionState& exc
     m_source->openIfInEndedState();
 
     // Steps 6 & beyond are handled by m_webSourceBuffer.
-    m_webSourceBuffer->append(data->data(), data->length());
+
+    // Use null for |timestampOffset| parameter because the prefixed API does not allow appends
+    // to update timestampOffset.
+    m_webSourceBuffer->append(data->data(), data->length(), 0);
 }
 
 void WebKitSourceBuffer::abort(ExceptionState& exceptionState)

third_party/WebKit/public/platform/WebSourceBuffer.h

@@ -45,7 +45,11 @@ public:
     virtual ~WebSourceBuffer() { }
     virtual bool setMode(AppendMode) = 0;
     virtual WebTimeRanges buffered() = 0;
-    virtual void append(const unsigned char* data, unsigned length) = 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;
+
     virtual void abort() = 0;
     virtual void remove(double start, double end) = 0;
     virtual bool setTimestampOffset(double) = 0;