Infrastructure for temportarily relinquishing GPU resources.

ui/ozone/common/gpu/ozone_gpu_messages.h

 // Copyright 2014 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.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <vector>
 
 #include "ipc/ipc_message_macros.h"
@@ skipping 81 matching lines @@
 
 IPC_MESSAGE_CONTROL1(OzoneGpuMsg_DisableNativeDisplay,
                      int64_t)  // display ID
 
 // Take control of the display
 IPC_MESSAGE_CONTROL0(OzoneGpuMsg_TakeDisplayControl)
 
 // Let other entity control the display
 IPC_MESSAGE_CONTROL0(OzoneGpuMsg_RelinquishDisplayControl)
 
+// Tells the GPU process to relinquish the display to an external process.
+// Creating a new surface will automatically re-acquire the display.
+IPC_MESSAGE_CONTROL0(OzoneGpuMsg_RelinquishDisplay)

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

Where is the code that uses this new message?

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

This and OzoneHostMsg_ResourcesRelinquished below are used to communicate
between the browser and GPU processes by the internal Cast ozone_platform which
has vendor-specific code which we cannot open-source.

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

I'm not a big fan of adding messages that have no (visible) users, nor an
implementation. For the purpose of the chromium project, it has no value.

I like spang@'s suggestion. A single cross-platform message that does generic
cleanup as well as platform-specific cleanup. The platform specifics is hidden
behind an ozone API.

+
 //------------------------------------------------------------------------------
 // Browser Messages
 // These messages are from the GPU to the browser process.
 
 // Updates the list of active displays.
 IPC_MESSAGE_CONTROL1(OzoneHostMsg_UpdateNativeDisplays,
                      std::vector<ui::DisplaySnapshot_Params>)
+
+// Response to OzoneGpuMsg_RelinquishDisplay
+IPC_MESSAGE_CONTROL0(OzoneHostMsg_ResourcesRelinquished)