Enable test LayerTreeHostTestBreakSwapPromise with verbose logging information

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 453c75cb54daa5ae60dd8a7965dc20ac6e0ebc3c..a4a31d24d03b113a522567c5e929286b5b7989ac 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -4468,11 +4468,19 @@ class TestSwapPromise : public SwapPromise {
 
   virtual ~TestSwapPromise() {
     base::AutoLock lock(result_->lock);
+    LOG(ERROR) << "~TestSwapPromise() "
+               << " did_swap_called " << result_->did_swap_called
+               << " did_not_swap_called " << result_->did_not_swap_called
+               << " result addr " << result_;
     result_->dtor_called = true;
   }
 
   virtual void DidSwap(CompositorFrameMetadata* metadata) OVERRIDE {
     base::AutoLock lock(result_->lock);
+    LOG(ERROR) << "TestSwapPromise::DidSwap "
+               << " did_swap_called " << result_->did_swap_called
+               << " did_not_swap_called " << result_->did_not_swap_called
+               << " result addr " << result_;
     EXPECT_FALSE(result_->did_swap_called);
     EXPECT_FALSE(result_->did_not_swap_called);
     result_->did_swap_called = true;
@@ -4480,6 +4488,11 @@ class TestSwapPromise : public SwapPromise {
 
   virtual void DidNotSwap(DidNotSwapReason reason) OVERRIDE {
     base::AutoLock lock(result_->lock);
+    LOG(ERROR) << "TestSwapPromise::DidNotSwap "
+               << " reason " << reason
+               << " did_swap_called " << result_->did_swap_called
+               << " did_not_swap_called " << result_->did_not_swap_called
+               << " result addr " << result_;
     EXPECT_FALSE(result_->did_swap_called);
     EXPECT_FALSE(result_->did_not_swap_called);
     result_->did_not_swap_called = true;
@@ -4563,7 +4576,8 @@ class LayerTreeHostTestBreakSwapPromise : public LayerTreeHostTest {
 };
 
 // TODO(miletus): Flaky test: crbug.com/393995
-// MULTI_THREAD_TEST_F(LayerTreeHostTestBreakSwapPromise);
+// Enabled with verbose logging information.
+MULTI_THREAD_TEST_F(LayerTreeHostTestBreakSwapPromise);
 
 class LayerTreeHostTestBreakSwapPromiseForVisibilityAbortedCommit
     : public LayerTreeHostTest {