viz: Convert a sync api in ServerGpuMemoryBufferManager into async.

components/viz/common/server_gpu_memory_buffer_manager.h

Index: components/viz/common/server_gpu_memory_buffer_manager.h
diff --git a/components/viz/common/server_gpu_memory_buffer_manager.h b/components/viz/common/server_gpu_memory_buffer_manager.h
index c34eda825d3ec8e20583999d874e6aa90c1ad15e..a1f9e99ab8e1df1566b77983495e5139e544be8f 100644
--- a/components/viz/common/server_gpu_memory_buffer_manager.h
+++ b/components/viz/common/server_gpu_memory_buffer_manager.h
@@ -9,7 +9,8 @@
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
-#include "base/threading/thread_checker.h"
+#include "base/single_thread_task_runner.h"

[danakj, 2017/06/15 23:02:42]

sequenced (and forward declare?)

+#include "base/synchronization/waitable_event.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 #include "gpu/ipc/host/gpu_memory_buffer_support.h"
 
@@ -23,8 +24,7 @@ namespace viz {
 
 // This GpuMemoryBufferManager implementation is for [de]allocating gpu memory
 // from the gpu process over the mojom.GpuService api.
-class ServerGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager,
-                                     public base::ThreadChecker {
+class ServerGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager {
  public:
   ServerGpuMemoryBufferManager(ui::mojom::GpuService* gpu_service,
                                int client_id);
@@ -36,13 +36,14 @@ class ServerGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager,
 
   void DestroyAllGpuMemoryBufferForClient(int client_id);
 
-  gfx::GpuMemoryBufferHandle CreateGpuMemoryBufferHandle(
+  void AllocateGpuMemoryBuffer(
       gfx::GpuMemoryBufferId id,
       int client_id,
       const gfx::Size& size,
       gfx::BufferFormat format,
       gfx::BufferUsage usage,
-      gpu::SurfaceHandle surface_handle);
+      gpu::SurfaceHandle surface_handle,
+      base::OnceCallback<void(const gfx::GpuMemoryBufferHandle&)> callback);
 
   // Overridden from gpu::GpuMemoryBufferManager:
   std::unique_ptr<gfx::GpuMemoryBuffer> CreateGpuMemoryBuffer(

[danakj, 2017/06/15 23:02:42]

Please document threading restrictions clearly here for this method. Also
perhaps for all other methods in the class comment? Also how about adding
OnFooThread suffixes to every method that isn't the interface? OnOriginThread
for the thread this is created on?

Alternatively.. we could push this impl out to a member nested class which calls
back to this outer class...? would that make the threading model clear also?

[sadrul, 2017/06/16 12:52:19]

I can comment on the interface [1] that this can be called from any thread.
Other than that, the rest of the functions in this class are expected to be
called on the same thread (see DCHECK()s).

[1]
https://cs.chromium.org/chromium/src/gpu/command_buffer/client/gpu_memory_buf...

[danakj, 2017/06/20 16:27:26]

That'd be good, and a top level class comment explaining what you just said here
also.

[sadrul, 2017/06/20 18:21:02]

Done.

@@ -54,6 +55,15 @@ class ServerGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager,
                                const gpu::SyncToken& sync_token) override;
 
  private:
+  void OnGpuMemoryBufferAllocated(
+      int client_id,
+      base::OnceCallback<void(const gfx::GpuMemoryBufferHandle&)> callback,
+      const gfx::GpuMemoryBufferHandle& handle);
+  void SignalGpuMemoryBufferAllocated(
+      gfx::GpuMemoryBufferHandle* handle,
+      base::WaitableEvent* wait_event,
+      const gfx::GpuMemoryBufferHandle& allocated_buffer_handle);
+
   ui::mojom::GpuService* gpu_service_;
   const int client_id_;
   int next_gpu_memory_id_ = 1;
@@ -62,8 +72,10 @@ class ServerGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager,
       std::unordered_set<gfx::GpuMemoryBufferId,
                          BASE_HASH_NAMESPACE::hash<gfx::GpuMemoryBufferId>>;
   std::unordered_map<int, NativeBuffers> native_buffers_;
+  std::unordered_set<int> pending_buffers_;
 
   const gpu::GpuMemoryBufferConfigurationSet native_configurations_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
   base::WeakPtrFactory<ServerGpuMemoryBufferManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServerGpuMemoryBufferManager);