Expedite discovery of primary DRM device.

ui/ozone/public/gpu_platform_support_host.h

 // Copyright 2014 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 UI_OZONE_PUBLIC_GPU_PLATFORM_SUPPORT_HOST_H_
 #define UI_OZONE_PUBLIC_GPU_PLATFORM_SUPPORT_HOST_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
 #include "ui/ozone/ozone_base_export.h"
 
 namespace ui {
 
 // Platform-specific object to support a GPU process host.
 //
 // ChromeOS on bare hardware will do display configuration and cursor
 // movement from the GPU process. This provides a conduit for the
 // messages needed to make this work.
 //
 // Under X11, we don't need any GPU messages for display configuration.
 // That's why there's no real functionality here: it's purely mechanism
 // to support additional messages needed by specific platforms.
 class OZONE_BASE_EXPORT GpuPlatformSupportHost : public IPC::Listener {
  public:
   GpuPlatformSupportHost();
   ~GpuPlatformSupportHost() override;
 
-  // Called when the GPU process is spun up & channel established.
-  virtual void OnChannelEstablished(
+  // Called when the GPU process is spun up.
+  // This is called from browser IO thread.
+  virtual void OnGpuProcessLaunched(
       int host_id,
       scoped_refptr<base::SingleThreadTaskRunner> send_runner,
       const base::Callback<void(IPC::Message*)>& sender) = 0;
 
+  // Called when the channel is established.
+  // This is called from browser UI thread.
+  virtual void OnChannelEstablished() = 0;
+
   // Called when the GPU process is destroyed.
+  // This is called from browser UI thread.
   virtual void OnChannelDestroyed(int host_id) = 0;
 };
 
 // create a stub implementation.
 OZONE_BASE_EXPORT GpuPlatformSupportHost* CreateStubGpuPlatformSupportHost();
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_GPU_PLATFORM_SUPPORT_HOST_H_