gpu: Notify callbacks the reason for channel creation failure

content/browser/gpu/gpu_process_host.h

 // 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.
 
 #ifndef CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_
 #define CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 48 matching lines @@
                        public IPC::Sender,
                        public ui::mojom::GpuHost,
                        public base::NonThreadSafe {
  public:
   enum GpuProcessKind {
     GPU_PROCESS_KIND_UNSANDBOXED,
     GPU_PROCESS_KIND_SANDBOXED,
     GPU_PROCESS_KIND_COUNT
   };
 
-  typedef base::Callback<void(const IPC::ChannelHandle&, const gpu::GPUInfo&)>
-      EstablishChannelCallback;
+  enum class EstablishChannelStatus {
+    GPU_ACCESS_DENIED,  // GPU access was not allowed.
+    GPU_HOST_INVALID,   // Request failed because the gpu host became invalid
+                        // while processing the request (e.g. the gpu process
+                        // may have been killed). The caller should normally
+                        // make another request to establish a new channel.
+    SUCCESS
+  };
+  using EstablishChannelCallback =
+      base::Callback<void(const IPC::ChannelHandle&,
+                          const gpu::GPUInfo&,
+                          EstablishChannelStatus status)>;
 
   typedef base::Callback<void(const gfx::GpuMemoryBufferHandle& handle)>
       CreateGpuMemoryBufferCallback;
 
   static bool gpu_enabled() { return gpu_enabled_; }
   static int gpu_crash_count() { return gpu_crash_count_; }
 
   // Creates a new GpuProcessHost (if |force_create| is turned on) or gets an
   // existing one, resulting in the launching of a GPU process if required.
   // Returns null on failure. It is not safe to store the pointer once control
@@ skipping 204 matching lines @@
   gpu::GpuProcessHostActivityFlags activity_flags_;
 
   base::WeakPtrFactory<GpuProcessHost> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuProcessHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_