Fix the MessageLoop type in case more than one ozone platform is built

ui/ozone/public/ozone_platform.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_OZONE_PLATFORM_H_
 #define UI_OZONE_PUBLIC_OZONE_PLATFORM_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/message_loop/message_loop.h"
 #include "ui/ozone/ozone_export.h"
 
 namespace display {
 class NativeDisplayDelegate;
 }
 
 namespace gfx {
 class Rect;
 }
 
@@ skipping 43 matching lines @@
     // must set this parameter in order for the Ozone platform implementation to
     // be able to use Mojo.
     service_manager::Connector* connector = nullptr;
 
     // Setting this to true indicates that the platform implementation should
     // operate as a single process for platforms (i.e. drm) that are usually
     // split between a main and gpu specific portion.
     bool single_process = false;
   };
 
+  // Creates the OzonePlatform instance without doing any initialization.
+  // This is useful in order call virtual methods that depend on the ozone
+  // platform selected at runtime, e.g. ::GetMessageLoopTypeForGpu,

[Ken Russell (switch to Gerrit), 2017/02/08 04:57:45]

Document that this is idempotent, and has no effect if the platform's already
been instantiated and initialized. At least, I hope those are the semantics.

[tonikitoo, 2017/02/08 06:42:08]

Done.

+  static void CreateInstance();
+
   // Initializes the subsystems/resources necessary for the UI process (e.g.
   // events, etc.)
   // TODO(rjkroege): Remove deprecated entry point (http://crbug.com/620934)
   static void InitializeForUI();
 
   // Initializes the subsystems/resources necessary for the UI process (e.g.
   // events) with additional properties to customize the ozone platform
   // implementation. Ozone will not retain InitParams after returning from
   // InitalizeForUI.
   static void InitializeForUI(const InitParams& args);
@@ skipping 17 matching lines @@
   virtual ui::InputController* GetInputController() = 0;
   virtual IPC::MessageFilter* GetGpuMessageFilter();
   virtual ui::GpuPlatformSupportHost* GetGpuPlatformSupportHost() = 0;
   virtual std::unique_ptr<SystemInputInjector> CreateSystemInputInjector() = 0;
   virtual std::unique_ptr<PlatformWindow> CreatePlatformWindow(
       PlatformWindowDelegate* delegate,
       const gfx::Rect& bounds) = 0;
   virtual std::unique_ptr<display::NativeDisplayDelegate>
   CreateNativeDisplayDelegate() = 0;
 
+  // Returns the message loop type required for OzonePlatform instance that
+  // will be initialized for the GPU process.
+  virtual base::MessageLoop::Type GetMessageLoopTypeForGpu();
+
   // Ozone platform implementations may also choose to expose mojo interfaces to
   // internal functionality. Embedders wishing to take advantage of ozone mojo
   // implementations must invoke AddInterfaces with a valid
   // service_manager::InterfaceRegistry* pointer to export all Mojo interfaces
   // defined within Ozone.
   //
   // A default do-nothing implementation is provided to permit platform
   // implementations to opt out of implementing any Mojo interfaces.
   virtual void AddInterfaces(service_manager::InterfaceRegistry* registry);
 
  private:
   virtual void InitializeUI() = 0;
   virtual void InitializeGPU() = 0;
   virtual void InitializeUI(const InitParams& args);
   virtual void InitializeGPU(const InitParams& args);
 
-  static void CreateInstance();
-
   static OzonePlatform* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(OzonePlatform);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_OZONE_PLATFORM_H_