Use GVR async reprojection video surface for fullscreen in VR shell

chrome/browser/android/vr_shell/vr_shell.h

Index: chrome/browser/android/vr_shell/vr_shell.h
diff --git a/chrome/browser/android/vr_shell/vr_shell.h b/chrome/browser/android/vr_shell/vr_shell.h
index 435ef38182bb96a0144335ab42e82d8d85c25da3..dead3020309ecebbb096b3f407e74bd3d2651a6b 100644
--- a/chrome/browser/android/vr_shell/vr_shell.h
+++ b/chrome/browser/android/vr_shell/vr_shell.h
@@ -14,10 +14,13 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
+#include "content/public/browser/android/video_surface_provider.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "device/vr/android/gvr/gvr_delegate.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr_types.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gl/android/scoped_java_surface.h"
 
 namespace base {
 class ListValue;
@@ -54,7 +57,8 @@ class VrMetricsHelper;
 
 // The native instance of the Java VrShell. This class is not threadsafe and
 // must only be used on the UI thread.
-class VrShell : public device::GvrDelegate, content::WebContentsObserver {
+class VrShell : public device::GvrDelegate, content::WebContentsObserver,
+  content::VideoSurfaceProvider {
  public:
   VrShell(JNIEnv* env, jobject obj,
           content::WebContents* main_contents,
@@ -131,6 +135,12 @@ class VrShell : public device::GvrDelegate, content::WebContentsObserver {
 
   void ContentFrameWasResized(bool width_changed);
 
+  // Called by the Java class when the video surface changes.
+  void SetVideoSurface(JNIEnv* env,
+                  const base::android::JavaParamRef<jobject>& obj,
+                  const base::android::JavaParamRef<jobject>& surface);
+
+
   void ForceExitVr();
 
  private:
@@ -144,6 +154,12 @@ class VrShell : public device::GvrDelegate, content::WebContentsObserver {
   void MainFrameWasResized(bool width_changed) override;
   void WebContentsDestroyed() override;
 
+  // content::VideoSurfaceProvider implementation. (not sure what thread).
+  void OnVideoSizeChanged(int width, int height) override;
+  void CreateVideoSurface(content::VideoSurfaceProvider::Client* client,
+                          const gfx::Size& video_natural_size) override;
+  content::VideoSurfaceProvider::Client* client_;
+
   std::unique_ptr<UiInterface> html_interface_;
 
   content::WebContents* main_contents_;