Checking RendererThreadImpl for null when creating media player.

content/renderer/render_frame_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_frame_impl.h"
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 2717 matching lines @@
   if (!web_stream.isNull())
     return CreateWebMediaPlayerForMediaStream(client, sink_id,
                                               frame_->getSecurityOrigin());
 
   // If |source| was not a MediaStream, it must be a URL.
   // TODO(guidou): Fix this when support for other srcObject types is added.
   DCHECK(source.isURL());
   blink::WebURL url = source.getAsURL();
 
   RenderThreadImpl* render_thread = RenderThreadImpl::current();
+  // Render thread may not exist in tests:

[Avi (use Gerrit), 2016/10/31 14:45:29]

Make comments be complete sentences, ending in a .

[o1ka, 2016/10/31 14:58:38]

Done.

+  if (!render_thread)
+    return nullptr;
 
   scoped_refptr<media::SwitchableAudioRendererSink> audio_renderer_sink =
       AudioDeviceFactory::NewSwitchableAudioRendererSink(
           AudioDeviceFactory::kSourceMediaElement, routing_id_, 0,
           sink_id.utf8(), frame_->getSecurityOrigin());
   // We need to keep a reference to the context provider (see crbug.com/610527)
   // but media/ can't depend on cc/, so for now, just keep a reference in the
   // callback.
   // TODO(piman): replace media::Context3D to scoped_refptr<ContextProvider> in
   // media/ once ContextProvider is in gpu/.
@@ skipping 3867 matching lines @@
   // event target. Potentially a Pepper plugin will receive the event.
   // In order to tell whether a plugin gets the last mouse event and which it
   // is, we set |pepper_last_mouse_event_target_| to null here. If a plugin gets
   // the event, it will notify us via DidReceiveMouseEvent() and set itself as
   // |pepper_last_mouse_event_target_|.
   pepper_last_mouse_event_target_ = nullptr;
 #endif
 }
 
 }  // namespace content