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 c60611fde052955cc17c1e312d2c410df4e09b8a..a756a1ee1cc8f30dd2f790b4b00819de9e5b4cb8 100644
--- a/Source/web/SourceBufferPrivateImpl.cpp
+++ b/Source/web/SourceBufferPrivateImpl.cpp
@@ -70,6 +70,20 @@ 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()
 {
     m_sourceBuffer->removedFromMediaSource();