GPU Channel's now maintain a global order number for each processed IPC.

content/common/gpu/gpu_channel_manager.h

Index: content/common/gpu/gpu_channel_manager.h
diff --git a/content/common/gpu/gpu_channel_manager.h b/content/common/gpu/gpu_channel_manager.h
index 8122c2bde1c012411eac80e5704c16965bf37613..e9c3f918dbb4e6190226bf96138e656608ccc468 100644
--- a/content/common/gpu/gpu_channel_manager.h
+++ b/content/common/gpu/gpu_channel_manager.h
@@ -13,6 +13,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "build/build_config.h"
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
@@ -83,7 +84,7 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
   bool Send(IPC::Message* msg) override;
 
   bool HandleMessagesScheduled();
-  uint64 MessagesProcessed();
+  uint32_t ProcessedOrderNumber();
 
   void LoseAllContexts();
 
@@ -91,6 +92,8 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
   void AddRoute(int32 routing_id, IPC::Listener* listener);
   void RemoveRoute(int32 routing_id);
 
+  uint32_t GenerateGlobalOrderNumber();
+
   gpu::gles2::ProgramCache* program_cache();
   gpu::gles2::ShaderTranslatorCache* shader_translator_cache();
   gpu::gles2::FramebufferCompletenessCache* framebuffer_completeness_cache();
@@ -153,9 +156,13 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
                           const gpu::ValueState& state);
   void OnLoseAllContexts();
 
+  // Thread Checkers.
+  base::ThreadChecker io_thread_checker_;
+
   // Used to send and receive IPC messages from the browser process.
   IPC::SyncChannel* const channel_;
   MessageRouter router_;
+  uint32_t global_order_counter_;

[piman, 2015/08/31 23:15:04]

Use a AtomicSequenceNumber, then you don't need extra thread checks.

[David Yen, 2015/09/01 02:01:52]

This number is only operated on from the IO thread so it doesn't need to be
atomic. But since I've moved it to the GpuChannelMessageFilter as a private
static number, I don't think the thread checker is necessary anymore since it's
easier to verify that it is only called from the IO thread.

 
   GpuWatchdog* watchdog_;