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

ui/ozone/platform/dri/ozone_platform_gbm.cc

Index: ui/ozone/platform/dri/ozone_platform_gbm.cc
diff --git a/ui/ozone/platform/dri/ozone_platform_gbm.cc b/ui/ozone/platform/dri/ozone_platform_gbm.cc
index 20f9450133b9f9acb03ec5ec33220795ca6006ab..a2f59e7c29f7284967e6482edd3b7cd6265f361e 100644
--- a/ui/ozone/platform/dri/ozone_platform_gbm.cc
+++ b/ui/ozone/platform/dri/ozone_platform_gbm.cc
@@ -19,6 +19,7 @@
 #include "ui/ozone/platform/dri/dri_cursor.h"
 #include "ui/ozone/platform/dri/dri_gpu_platform_support.h"
 #include "ui/ozone/platform/dri/dri_gpu_platform_support_host.h"
+#include "ui/ozone/platform/dri/dri_helper_thread.h"
 #include "ui/ozone/platform/dri/dri_window.h"
 #include "ui/ozone/platform/dri/dri_window_delegate_manager.h"
 #include "ui/ozone/platform/dri/dri_window_manager.h"
@@ -148,8 +149,11 @@ class OzonePlatformGbm : public OzonePlatform {
 
   void InitializeGPU() override {
     gl_api_loader_.reset(new GlApiLoader());
+    if (use_surfaceless_)
+      helper_thread_.reset(new DriHelperThread());
+
     // Async page flips are supported only on surfaceless mode.
-    gbm_.reset(new GbmWrapper(kDefaultGraphicsCardPath, !use_surfaceless_));
+    gbm_.reset(new GbmWrapper(kDefaultGraphicsCardPath, helper_thread_.get()));
     gbm_->Initialize();
     buffer_generator_.reset(new GbmBufferGenerator());
     screen_manager_.reset(
@@ -163,14 +167,15 @@ class OzonePlatformGbm : public OzonePlatform {
     scoped_ptr<NativeDisplayDelegateDri> ndd(
         new NativeDisplayDelegateDri(gbm_.get(), screen_manager_.get()));
     ndd->Initialize();
-    gpu_platform_support_.reset(
-        new DriGpuPlatformSupport(gbm_.get(), window_delegate_manager_.get(),
-                                  screen_manager_.get(), ndd.Pass()));
+    gpu_platform_support_.reset(new DriGpuPlatformSupport(
+        gbm_.get(), window_delegate_manager_.get(), screen_manager_.get(),
+        helper_thread_.get(), ndd.Pass()));
   }
 
  private:
   bool use_surfaceless_;
   scoped_ptr<GlApiLoader> gl_api_loader_;
+  scoped_ptr<DriHelperThread> helper_thread_;
   scoped_ptr<GbmWrapper> gbm_;
   scoped_ptr<GbmBufferGenerator> buffer_generator_;
   scoped_ptr<ScreenManager> screen_manager_;