Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index 145376273cbd06bc231e33d5d5db9efe6e0bb6e2..7eeadc62385eac9ca84527b52319ea33dc6eb3cd 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -11,6 +11,7 @@
 #include "base/callback.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "content/browser/renderer_host/image_transport_factory.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/content_export.h"
@@ -49,7 +50,8 @@ class RenderWidgetHostViewAura
       public ui::TextInputClient,
       public aura::WindowDelegate,
       public aura::client::ActivationDelegate,
-      public ImageTransportFactoryObserver {
+      public ImageTransportFactoryObserver,
+      public base::SupportsWeakPtr<RenderWidgetHostViewAura> {
  public:
   // RenderWidgetHostView implementation.
   virtual void InitAsChild(gfx::NativeView parent_view) OVERRIDE;
@@ -239,6 +241,21 @@ class RenderWidgetHostViewAura
   // Called when window_ is removed from the window tree.
   void RemovingFromRootWindow();
 
+  // After clearing |current_surface_|, and waiting for the compositor to finish
+  // using it, call this to inform the gpu process.
+  void SetSurfaceNotInUseByCompositor(ui::Compositor* compositor);
+
+  // This is called every time |current_surface_| usage changes (by thumbnailer,
+  // compositor draws, and tab visibility). Every time usage of current surface
+  // changes between "may be used" and "certain to not be used" by the ui, we
+  // inform the gpu process.
+  void AdjustSurfaceProtection();
+
+  // Called after async thumbnailer task completes.  Used to call
+  // AdjustSurfaceProtection.
+  void CopyFromCompositingSurfaceFinished(base::Callback<void(bool)> callback,
+                                          bool result);
+
   ui::Compositor* GetCompositor();
 
   // Detaches |this| from the input method object.
@@ -307,6 +324,20 @@ class RenderWidgetHostViewAura
 
   uint64 current_surface_;
 
+  // Protected means that the |current_surface_| may be in use by ui and cannot
+  // be safely discarded. Things to consider are thumbnailer, compositor draw,
+  // and tab visibility.
+  bool current_surface_is_protected_;
+  bool current_surface_in_use_by_compositor_;
+
+  std::vector<base::Callback<void(bool)> > pending_thumbnail_tasks_;
+
+  // This id increments every time surface_is_protected changes. We tag IPC
+  // messages which rely on protection state with this id to stay in sync.
+  uint32 protection_state_id_;
+
+  int32 surface_route_id_;
+
   gfx::GLSurfaceHandle shared_surface_handle_;
 
   // If non-NULL we're in OnPaint() and this is the supplied canvas.