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 5bedc69d4ebd65fc2e059a508f92ab2590139767..96c652b048a8cfd9d019442ead74794e655cc7c7 100644
--- a/content/renderer/gpu/gpu_channel_host.cc
+++ b/content/renderer/gpu/gpu_channel_host.cc
@@ -182,7 +182,7 @@ 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,
@@ -205,7 +205,7 @@ CommandBufferProxy* GpuChannelHost::CreateViewCommandBuffer(
   int32 route_id;
   if (!ChildThread::current()->Send(
       new GpuHostMsg_CreateViewCommandBuffer(
-          render_view_id,
+          surface_id,
           init_params,
           &route_id))) {
     return NULL;