Fix logic in GpuChannelHost::Send() during shutdown.

RenderThread::current() returns NULL after the ~AtExitManager() has
processed its callbacks. However, contexts still referencing GpuChannelHost
might get destroyed on the main thread only until later. In that case we
want to avoid using the sync filter.
Also fix unreached code/leak while the channel is gone.

BUG=95734

Review URL: http://codereview.chromium.org/7841053

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@100274 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 9 insertions, 3 deletions

diff --git a/content/renderer/gpu/gpu_channel_host.cc b/content/renderer/gpu/gpu_channel_host.cc
index d822316..00995ac 100644
--- a/content/renderer/gpu/gpu_channel_host.cc
+++ b/content/renderer/gpu/gpu_channel_host.cc
@@ -179,12 +179,18 @@ bool GpuChannelHost::Send(IPC::Message* message) {
   // preserve order.
   message->set_unblock(false);
 
-  // Unfortunately a sync filter cannot be used on the main (listener) thread.
-  // TODO: Is that true even when we don't install a listener?
+  // Currently we need to choose between two different mechanisms for sending.
+  // On the main thread we use the regular channel Send() method, on another
+  // thread we use SyncMessageFilter. We also have to be careful interpreting
+  // RenderThread::current() since it might return NULL during shutdown, while
+  // we are actually calling from the main thread (discard message then).
+  //
+  // TODO: Can we just always use sync_filter_ since we setup the channel
+  //       without a main listener?
   if (RenderThread::current()) {
     if (channel_.get())
       return channel_->Send(message);
-  } else {
+  } else if (MessageLoop::current()) {
     return sync_filter_->Send(message);
   }