[Ozone-Dri] Decouple the IO helper thread from DriWrapper

ui/ozone/platform/dri/dri_wrapper.h

Index: ui/ozone/platform/dri/dri_wrapper.h
diff --git a/ui/ozone/platform/dri/dri_wrapper.h b/ui/ozone/platform/dri/dri_wrapper.h
index 0dfa86691363cdc21a7fca32d84cc669ed4ef790..381459ee7e0b3476ec14f3e569ac9ab14dffc803 100644
--- a/ui/ozone/platform/dri/dri_wrapper.h
+++ b/ui/ozone/platform/dri/dri_wrapper.h
@@ -12,7 +12,6 @@
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
-#include "base/threading/thread.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/overlay_transform.h"
@@ -24,6 +23,10 @@ typedef struct _drmModeModeInfo drmModeModeInfo;
 
 struct SkImageInfo;
 
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
 namespace ui {
 
 class HardwareDisplayPlaneManager;
@@ -37,12 +40,16 @@ class DriWrapper {
                               unsigned int /* seconds */,
                               unsigned int /* useconds */)> PageFlipCallback;
 
-  DriWrapper(const char* device_path, bool use_sync_flips);
+  DriWrapper(const char* device_path);
   virtual ~DriWrapper();
 
   // Open device.
   virtual void Initialize();
 
+  // |task_runner| will be used to asynchronously page flip.
+  virtual void InitializeTaskRunner(
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+
   // Get the CRTC state. This is generally used to save state before using the
   // CRTC. When the user finishes using the CRTC, the user should restore the
   // CRTC to it's initial state. Use |SetCrtc| to restore the state.
@@ -152,10 +159,6 @@ class DriWrapper {
   HardwareDisplayPlaneManager* plane_manager() { return plane_manager_.get(); }
 
  protected:
-  // Responsible for late initialization of the IO thread. This needs to happen
-  // after the sandbox is up, thus the late initialization.
-  virtual void InitializeIOWatcher();
-
   // The file descriptor associated with this wrapper. All DRM operations will
   // be performed using this FD.
   // TODO(dnicoara) Make this a base::File
@@ -163,9 +166,6 @@ class DriWrapper {
 
   scoped_ptr<HardwareDisplayPlaneManager> plane_manager_;
 
-  // If we need to block when performing page flips this is set to true.
-  bool use_sync_flips_;
-
  private:
   class IOWatcher;
 
@@ -173,9 +173,7 @@ class DriWrapper {
   const char* device_path_;
 
   // Helper thread to perform IO listener operations.
-  // TODO(dnicoara) This should really be supported by the main thread.
-  // Alternatively we should have a way to access the IO thread's task runner.
-  base::Thread io_thread_;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   // Watcher for |fd_| listening for page flip events.
   scoped_refptr<IOWatcher> watcher_;