Convert plugin and GPU process to brokered handle duplication.

content/common/gpu/gpu_messages.h

Index: content/common/gpu/gpu_messages.h
===================================================================
--- content/common/gpu/gpu_messages.h	(revision 132263)
+++ content/common/gpu/gpu_messages.h	(working copy)
@@ -216,11 +216,10 @@
 // A renderer sends this when it wants to create a connection to the GPU
 // process. The browser will create the GPU process if necessary, and will
 // return a handle to the channel via a GpuChannelEstablished message.
-IPC_SYNC_MESSAGE_CONTROL1_4(GpuHostMsg_EstablishGpuChannel,
+IPC_SYNC_MESSAGE_CONTROL1_3(GpuHostMsg_EstablishGpuChannel,
                             content::CauseForGpuLaunch,
                             int /* client id */,
                             IPC::ChannelHandle /* handle to channel */,
-                            base::ProcessHandle /* renderer_process_for_gpu */,
                             content::GPUInfo /* stats about GPU process*/)
 
 // A renderer sends this to the browser process when it wants to
@@ -292,13 +291,6 @@
 // GPU Channel Messages
 // These are messages from a renderer process to the GPU process.
 
-// Initialize a channel between a renderer process and a GPU process. The
-// renderer passes its process handle to the GPU process, which gives gives the
-// GPU process the ability to map handles from the renderer process. This must
-// be the first message sent on a newly connected channel.
-IPC_MESSAGE_CONTROL1(GpuChannelMsg_Initialize,
-                     base::ProcessHandle /* renderer_process_for_gpu */)
-
 // Tells the GPU process to create a new command buffer that renders to an
 // offscreen frame buffer.
 IPC_SYNC_MESSAGE_CONTROL2_1(GpuChannelMsg_CreateOffscreenCommandBuffer,