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

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <utility>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 1811 matching lines @@
 }
 
 // static
 void RenderWidgetHostImpl::AcknowledgePostSubBuffer(int32 route_id,
                                                     int gpu_host_id) {
   GpuProcessHostUIShim* ui_shim = GpuProcessHostUIShim::FromID(gpu_host_id);
   if (ui_shim)
     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
   // indicate that no callback is in progress (i.e. without this line
   // DelayedAutoResized will not get called again).
   new_auto_size_.SetSize(0, 0);
   if (!should_auto_resize_)
     return;
 
   OnRenderAutoResized(new_size);
 }
 
 }  // namespace content