Add SwapPromise support to LayerTreeHost and LayerTreeImpl

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index c79f3e515f15a5c54dfaaef35ca4da8ff370caf5..111f8441de376989b97477b28bcdc012b19eab2c 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -20,6 +20,7 @@
 #include "cc/animation/animation_events.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_vector.h"
+#include "cc/base/swap_promise.h"
 #include "cc/debug/micro_benchmark.h"
 #include "cc/debug/micro_benchmark_controller.h"
 #include "cc/input/input_handler.h"
@@ -328,6 +329,18 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
                               scoped_ptr<base::Value> value,
                               const MicroBenchmark::DoneCallback& callback);
 
+  // Call this function when you expect there to be a swap buffer and want to
+  // have something done when the swap buffer actaully happens. Provide a
+  // did_swap_callback in the SwapPromise to be called when swap buffer happens,

[jamesr, 2013/11/12 03:15:04]

what thread will these callbacks be invoked on?

[Yufeng Shen (Slow to review), 2013/11/13 21:05:04]

Please see the comments in thread_proxy.cc

+  // and a swap_aborted_callback to be called when the swap buffer is aborted (

[jamesr, 2013/11/12 03:15:04]

what about when the context is lost? see
LayerTreeHostClient::DidInitializeOutputSurface()

[Yufeng Shen (Slow to review), 2013/11/13 21:05:04]

We started an email thread "Swap Promises" discussing this.

+  // e.g. the next commit aborts, the next frame generated does not have actual
+  // damage).
+  void QueueSwapPromise(const SwapPromise& swap_promise);
+
+  bool HasQueuedSwapPromise();
+  void FinishSwapPromise();
+  void BreakSwapPromise(const std::string& msg);
+
  protected:
   LayerTreeHost(LayerTreeHostClient* client,
                 SharedBitmapManager* manager,
@@ -474,6 +487,8 @@ class CC_EXPORT LayerTreeHost : NON_EXPORTED_BASE(public RateLimiterClient) {
 
   SharedBitmapManager* shared_bitmap_manager_;
 
+  std::vector<SwapPromise> swap_promise_list_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };