Add Blink side support for SourceBuffer.appendWindowStart & SourceBuffer.appendWindowEnd.

Source/web/SourceBufferPrivateImpl.cpp

Index: Source/web/SourceBufferPrivateImpl.cpp
diff --git a/Source/web/SourceBufferPrivateImpl.cpp b/Source/web/SourceBufferPrivateImpl.cpp
index a4ab34dea37e77e73cfc04c24ad8c0b244407bca..5b10e0eaa19cd7dd1515dd6457b6a5af3b49b7da 100644
--- a/Source/web/SourceBufferPrivateImpl.cpp
+++ b/Source/web/SourceBufferPrivateImpl.cpp
@@ -74,6 +74,20 @@ bool SourceBufferPrivateImpl::setTimestampOffset(double offset)
     return m_sourceBuffer->setTimestampOffset(offset);
 }
 
+void SourceBufferPrivateImpl::setAppendWindowStart(double start)
+{
+    if (!m_sourceBuffer)
+        return;
+    m_sourceBuffer->setAppendWindowStart(start);
+}
+
+void SourceBufferPrivateImpl::setAppendWindowEnd(double end)
+{
+    if (!m_sourceBuffer)
+        return;
+    m_sourceBuffer->setAppendWindowEnd(end);
+}
+
 void SourceBufferPrivateImpl::removedFromMediaSource()
 {
     if (!m_sourceBuffer)