Remove the MessageLoop::DestructionObserver from mojo bindings.

content/browser/gpu/browser_gpu_channel_host_factory.cc

Index: content/browser/gpu/browser_gpu_channel_host_factory.cc
diff --git a/content/browser/gpu/browser_gpu_channel_host_factory.cc b/content/browser/gpu/browser_gpu_channel_host_factory.cc
index b9876e88fc117395ce1d11f1fe86f5e36836822f..7a3f339affb5f9a4bfbca5c99731a70f8887da40 100644
--- a/content/browser/gpu/browser_gpu_channel_host_factory.cc
+++ b/content/browser/gpu/browser_gpu_channel_host_factory.cc
@@ -198,6 +198,14 @@ void BrowserGpuChannelHostFactory::EstablishRequest::Cancel() {
   finished_ = true;
 }
 
+void BrowserGpuChannelHostFactory::CloseChannel() {
+  DCHECK(instance_);
+  if (instance_->gpu_channel_) {
+    instance_->gpu_channel_->DestroyChannel();
+    instance_->gpu_channel_ = nullptr;
+  }
+}
+
 bool BrowserGpuChannelHostFactory::CanUseForTesting() {
   return GpuDataManager::GetInstance()->GpuAccessAllowed(NULL);
 }