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

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index c0217685a5fc1badb219d13be1d50778aede8645..445c32ec8586c325e33e9fb6a15cc206aaf47051 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -1829,6 +1829,21 @@ void RenderWidgetHostImpl::AcknowledgePostSubBuffer(int32 route_id,
     ui_shim->Send(new AcceleratedSurfaceMsg_PostSubBufferACK(route_id));
 }
 
+#if defined(USE_AURA)
+// static
+void RenderWidgetHostImpl::SendFrontSurfaceIsProtected(

[sky, 2012/06/13 16:21:23]

What is aura specific here?

[mmocny, 2012/06/13 18:40:05]

On other platforms this is not needed, because it is safe for the gpu process to
release its handle to the front surface without invalidating the browser handle.
 It can then send a release/suspend message to the browser to finalize the
release.  If we tab switch during this time, it is still safe to display the old
content.  On aura, the browser needs to reset its handle and promise to no
longer use the surface before the gpu can release.  This message is how we
communicate that fact.

We could add it to all platforms and not use it (since they may potentially need
to use it in the future), but perhaps we can delay doing that until that need
arises?

On 2012/06/13 16:21:23, sky wrote:

+    bool is_protected,
+    uint32 protection_state_id,
+    int32 route_id,
+    int gpu_host_id) {
+  GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
+  if (ui_shim) {
+    ui_shim->Send(new AcceleratedSurfaceMsg_SetFrontSurfaceIsProtected(
+        route_id, is_protected, protection_state_id));
+  }
+}
+#endif
+
 void RenderWidgetHostImpl::DelayedAutoResized() {
   gfx::Size new_size = new_auto_size_;
   // Clear the new_auto_size_ since the empty value is used as a flag to