Infrastructure for temportarily relinquishing GPU resources.

content/browser/gpu/gpu_process_host_ui_shim.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/gpu/gpu_process_host_ui_shim.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
@@ skipping 162 matching lines @@
           ->OnMessageReceived(message))
     return true;
 #endif
 
   if (message.routing_id() != MSG_ROUTING_CONTROL)
     return false;
 
   return OnControlMessageReceived(message);
 }
 
+void GpuProcessHostUIShim::RelinquishGpuResources(
+      const base::Closure& callback) {
+  // We end up sending two messages to the GPU process. the first is handled by
+  // GpuChannelManager to release the default_offscreen_surface which
+  // may hold a pointer to the EGL display which is about to be released.
+  // The second is sent indirectly by the Ozone platform to release all
+  // remaining OpenGL and EGL resources. It calls the optional callback once
+  // this is completed and it is safe for an external process to access the GPU.
+  // A default implementation runs the callback immediately.
+  Send(new GpuMsg_DeleteDefaultOffscreenSurface());

[piman, 2014/11/18 20:55:34]

Would you not want to wait for an ack before calling the callback?

[GusFernandez, 2014/11/19 18:50:13]

This is done effectively by the next call. We only need to be synchronous with
the second (RelinquishGpuResources) API.

[piman, 2014/11/19 20:33:52]

But that's not true on !OZONE

+#if defined(USE_OZONE)
+  ui::OzonePlatform::GetInstance()->RelinquishGpuResources(callback);
+#else
+  if (!callback.is_null()) {
+    callback.Run();
+  }
+#endif
+}
+
 void GpuProcessHostUIShim::SimulateRemoveAllContext() {
   Send(new GpuMsg_Clean());
 }
 
 void GpuProcessHostUIShim::SimulateCrash() {
   Send(new GpuMsg_Crash());
 }
 
 void GpuProcessHostUIShim::SimulateHang() {
   Send(new GpuMsg_Hang());
@@ skipping 83 matching lines @@
 #endif
 }
 
 void GpuProcessHostUIShim::OnVideoMemoryUsageStatsReceived(
     const GPUVideoMemoryUsageStats& video_memory_usage_stats) {
   GpuDataManagerImpl::GetInstance()->UpdateVideoMemoryUsageStats(
       video_memory_usage_stats);
 }
 
 }  // namespace content