Created multi-process-friendly PowerMonitor interface.

content/common/gpu/gpu_channel.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.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "content/common/gpu/gpu_channel.h"
 
 #include <queue>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/power_monitor/power_monitor.h"
 #include "base/process_util.h"
 #include "base/rand_util.h"
 #include "base/strings/string_util.h"
 #include "base/timer.h"
 #include "content/common/gpu/gpu_channel_manager.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/gpu/sync_point_manager.h"
+#include "content/common/power_monitor_message_filter.h"
 #include "content/public/common/content_switches.h"
 #include "crypto/hmac.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/command_buffer/service/gpu_scheduler.h"
 #include "gpu/command_buffer/service/image_manager.h"
 #include "gpu/command_buffer/service/mailbox_manager.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_image.h"
@@ skipping 445 matching lines @@
       weak_factory_.GetWeakPtr()));
 
   filter_ = new GpuChannelMessageFilter(
       mailbox_manager_->private_key(),
       weak_ptr,
       gpu_channel_manager_->sync_point_manager(),
       base::MessageLoopProxy::current());
   io_message_loop_ = io_message_loop;
   channel_->AddFilter(filter_.get());
 
+  PowerMonitorBroadcastSource* power_monitor_source_ =
+      static_cast<PowerMonitorBroadcastSource*>(

[vandebo (ex-Chrome), 2013/06/26 21:40:33]

Is it easy to get at the original source instead of having to do this cast?

+      base::PowerMonitor::Get()->Source());
+  channel_->AddFilter(power_monitor_source_->MessageFilter());

[vandebo (ex-Chrome), 2013/06/26 21:40:33]

Is there ever a RemoveFilter call?  The concern is that it may be possible for
MessageFilter() to continue receiving messages after power_monitor_source has
been cleaned up/destroyed.

[Ken Russell (switch to Gerrit), 2013/06/27 13:08:23]

This setup doesn't look correct to me. You want to process control messages
coming from the browser process to the GPU process. As far as I can tell, the
recipient of the GPU-related control messages coming from the browser in
gpu_process_host.cc are handled in GpuChildThread::OnControlMessageReceived and
GpuChannelManager::OnMessageReceived. In fact, I don't see where those messages
would be re-dispatched to all of the GpuChannels that have been established
between renderer processes and the GPU process, and it looks to me like this
filter is being added only to those connections. Basically, I think that the
setup for receiving the power messages should be done in gpu_main.cc, after the
initialization of the GpuChildThread, and that you should add the MessageFilter
to the GpuChildThread's channel().

[bajones, 2013/07/01 20:21:58]

I don't see any examples of a filter being removed in the code base.

[bajones, 2013/07/01 20:21:58]

I've moved the addition of the message filter into gpu_main.cc as suggested,
which has the happy side effect of completely avoiding the nasty cast! 

+
   return true;
 }
 
 std::string GpuChannel::GetChannelName() {
   return channel_id_;
 }
 
 #if defined(OS_POSIX)
 int GpuChannel::TakeRendererFileDescriptor() {
   if (!channel_) {
@@ skipping 450 matching lines @@
   }
 }
 
 void GpuChannel::CacheShader(const std::string& key,
                              const std::string& shader) {
   gpu_channel_manager_->Send(
       new GpuHostMsg_CacheShader(client_id_, key, shader));
 }
 
 }  // namespace content