allow non-downloading pipeline to play without download rate monitoring.

media/base/pipeline_impl.cc

Index: media/base/pipeline_impl.cc
===================================================================
--- media/base/pipeline_impl.cc	(revision 111037)
+++ media/base/pipeline_impl.cc	(working copy)
@@ -1046,12 +1046,18 @@
     int bitrate = 0;
     if (demuxer_.get())
       bitrate = demuxer_->GetBitrate();
-    // Needs to be locked because most other calls to |download_rate_monitor_|
-    // occur on the renderer thread.
-    download_rate_monitor_.Start(
-        base::Bind(&PipelineImpl::OnCanPlayThrough, this), bitrate);
-    download_rate_monitor_.SetBufferedBytes(buffered_bytes_, base::Time::Now());
 
+    if (bitrate == 0) {
+      OnCanPlayThrough();
+    } else {
+      // Needs to be locked because most other calls to |download_rate_monitor_|
+      // occur on the renderer thread.
+      download_rate_monitor_.Start(
+          base::Bind(&PipelineImpl::OnCanPlayThrough, this), bitrate);
+      download_rate_monitor_.SetBufferedBytes(buffered_bytes_,
+                                              base::Time::Now());
+    }
+
     if (IsPipelineStopPending()) {
       // We had a pending stop request need to be honored right now.
       TearDownPipeline();