Add SwapPromise support to LayerTreeHost and LayerTreeImpl

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index b25f8c23a16c819caffa216eb4fa67a3f1eaaab5..ff8b9a3aa3e92d05a08a143c9c7b3d450f964ed6 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -10,6 +10,7 @@
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/metrics/histogram.h"
+#include "cc/base/swap_promise.h"
 #include "cc/debug/benchmark_instrumentation.h"
 #include "cc/input/input_handler.h"
 #include "cc/output/context_provider.h"
@@ -24,6 +25,8 @@
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/frame_time.h"
 
+namespace {
+
 // Measured in seconds.
 const double kSmoothnessTakesPriorityExpirationDelay = 0.25;
 
@@ -32,6 +35,22 @@ const double kCommitAndActivationDurationEstimationPercentile = 50.0;
 const double kDrawDurationEstimationPercentile = 100.0;
 const int kDrawDurationEstimatePaddingInMicroseconds = 0;
 
+class SwapPromiseChecker {
+ public:
+  explicit SwapPromiseChecker(cc::LayerTreeHost* layer_tree_host)
+        : layer_tree_host_(layer_tree_host) {}
+
+  ~SwapPromiseChecker() {
+    if (layer_tree_host_->HasQueuedSwapPromise())

[danakj, 2013/11/13 23:23:35]

Do you even need this? You could just always call Break and it just does nothing
if its empty?

[Yufeng Shen (Slow to review), 2013/11/14 22:09:55]

Done.

+      layer_tree_host_->BreakSwapPromise(cc::SwapPromise::COMMIT_FAILS);
+  }
+
+ private:
+  cc::LayerTreeHost* layer_tree_host_;
+};
+
+}  // namespace
+
 namespace cc {
 
 struct ThreadProxy::ReadbackRequest {
@@ -730,6 +749,11 @@ void ThreadProxy::BeginMainFrame(
     return;
   }
 
+  // If the commit finishes, LTH will transfer its swap promises to LTI.

[danakj, 2013/11/13 23:22:09]

Spell out LayerTreeHost and LayerTreeImpl

[Yufeng Shen (Slow to review), 2013/11/14 22:09:55]

Done.

+  // The dtor of SwapPromiseChecker will check LTH's swap promises, and

[danakj, 2013/11/13 23:22:09]

destructor

check the LayerTreeHost's swap promises

[Yufeng Shen (Slow to review), 2013/11/14 22:09:55]

Done.

+  // break those swap promises if the commit ever aborts.
+  SwapPromiseChecker swap_promise_checker(layer_tree_host_);
+
   // Do not notify the impl thread of commit requests that occur during
   // the apply/animate/layout part of the BeginMainFrameAndCommit process since
   // those commit requests will get painted immediately. Once we have done
@@ -1109,6 +1133,11 @@ DrawSwapReadbackResult ThreadProxy::DrawSwapReadbackInternal(
   } else if (draw_frame) {
     DCHECK(swap_requested);
     result.did_swap = layer_tree_host_impl_->SwapBuffers(frame);
+    if (result.did_swap)
+      layer_tree_host_impl_->active_tree()->FinishSwapPromise();
+    else
+      layer_tree_host_impl_->active_tree()->BreakSwapPromise(
+          SwapPromise::SWAP_FAILS);
 
     // We don't know if we have incomplete tiles if we didn't actually swap.
     if (result.did_swap) {