mus: Avoid a crash when the gpu mojom connection is lost.

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 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_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 1845 matching lines @@
     scoped_refptr<FrameSwapMessageQueue> frame_swap_message_queue,
     const GURL& url) {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kDisableGpuCompositing))
     use_software = true;
 
 #if defined(USE_AURA)
   if (!use_software && IsRunningInMash() &&
       !command_line.HasSwitch(switches::kNoUseMusInRenderer)) {
+    scoped_refptr<gpu::GpuChannelHost> channel = EstablishGpuChannelSync();
+    // If the channel could not be established correctly, then return null. This
+    // would cause the compositor to wait and try again at a later time.
+    if (!channel)
+      return nullptr;
     return RendererWindowTreeClient::Get(routing_id)
         ->CreateCompositorFrameSink(
-            frame_sink_id,
-            gpu_->CreateContextProvider(EstablishGpuChannelSync()),
+            frame_sink_id, gpu_->CreateContextProvider(std::move(channel)),
             GetGpuMemoryBufferManager());
   }
 #endif
 
   uint32_t compositor_frame_sink_id = g_next_compositor_frame_sink_id++;
 
   if (command_line.HasSwitch(switches::kEnableVulkan)) {
     scoped_refptr<cc::VulkanContextProvider> vulkan_context_provider =
         cc::VulkanInProcessContextProvider::Create();
     if (vulkan_context_provider) {
@@ skipping 508 matching lines @@
   }
 }
 
 void RenderThreadImpl::OnRendererInterfaceRequest(
     mojom::RendererAssociatedRequest request) {
   DCHECK(!renderer_binding_.is_bound());
   renderer_binding_.Bind(std::move(request));
 }
 
 }  // namespace content