Add reference-counting for mailbox textures.

content/common/gpu/gpu_channel_manager.cc

Index: content/common/gpu/gpu_channel_manager.cc
diff --git a/content/common/gpu/gpu_channel_manager.cc b/content/common/gpu/gpu_channel_manager.cc
index fc48010ca1c36b819bd8211871e1e7f1e3f0649f..fbc99b7cad655d9889a23bd5add973f4ae8b448d 100644
--- a/content/common/gpu/gpu_channel_manager.cc
+++ b/content/common/gpu/gpu_channel_manager.cc
@@ -4,6 +4,8 @@
 
 #include "content/common/gpu/gpu_channel_manager.h"
 
+#include <utility>
+
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "content/common/child_thread.h"
@@ -105,6 +107,7 @@ bool GpuChannelManager::OnMessageReceived(const IPC::Message& msg) {
     IPC_MESSAGE_HANDLER(GpuMsg_CreateImage, OnCreateImage)
     IPC_MESSAGE_HANDLER(GpuMsg_DeleteImage, OnDeleteImage)
     IPC_MESSAGE_HANDLER(GpuMsg_LoadedShader, OnLoadedShader)
+    IPC_MESSAGE_HANDLER(GpuMsg_DestroySurface, OnDestroySurface)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP_EX()
   return handled;
@@ -259,6 +262,16 @@ void GpuChannelManager::OnLoadedShader(std::string program_proto) {
     program_cache()->LoadProgram(program_proto);
 }
 
+void GpuChannelManager::OnDestroySurface(int client_id,
+                                         int route_id,
+                                         int surface_id) {
+  if (mailbox_manager_) {
+    GpuChannel* channel = LookupChannel(client_id);
+    if (channel)
+      channel->OnDestroySurface(route_id, surface_id);
+  }
+}
+
 bool GpuChannelManager::HandleMessagesScheduled() {
   for (GpuChannelMap::iterator iter = gpu_channels_.begin();
        iter != gpu_channels_.end(); ++iter) {