gpu: reference target surfaces through a globally unique surface id.

content/renderer/gpu/gpu_channel_host.cc

Index: content/renderer/gpu/gpu_channel_host.cc
diff --git a/content/renderer/gpu/gpu_channel_host.cc b/content/renderer/gpu/gpu_channel_host.cc
index 6e3038c388d9104a600ae86e269de19f97d2c902..917733608ffb045292cd534371ba07026161d1fe 100644
--- a/content/renderer/gpu/gpu_channel_host.cc
+++ b/content/renderer/gpu/gpu_channel_host.cc
@@ -193,7 +193,7 @@ bool GpuChannelHost::Send(IPC::Message* message) {
 }
 
 CommandBufferProxy* GpuChannelHost::CreateViewCommandBuffer(
-    int render_view_id,
+    int32 surface_id,
     CommandBufferProxy* share_group,
     const std::string& allowed_extensions,
     const std::vector<int32>& attribs,
@@ -216,7 +216,7 @@ CommandBufferProxy* GpuChannelHost::CreateViewCommandBuffer(
   int32 route_id;
   if (!ChildThread::current()->Send(
       new GpuHostMsg_CreateViewCommandBuffer(
-          render_view_id,
+          surface_id,
           init_params,
           &route_id))) {
     return NULL;