Make RenderViewImpl::OnForceRedraw more robust

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index ff5da70a7e7ec633092d56de8cc7282b1316b21e..83502b88e7e04e985459ae813fc0725770a2cf8e 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1483,11 +1483,16 @@ void LayerTreeImpl::QueuePinnedSwapPromise(
 }
 
 void LayerTreeImpl::PassSwapPromises(
-    std::vector<std::unique_ptr<SwapPromise>>* new_swap_promise) {
-  for (const auto& swap_promise : swap_promise_list_)
-    swap_promise->DidNotSwap(SwapPromise::SWAP_FAILS);
+    std::vector<std::unique_ptr<SwapPromise>>* new_swap_promises) {
+  for (auto& swap_promise : swap_promise_list_) {
+    if (swap_promise->DidNotSwap(SwapPromise::SWAP_FAILS)) {
+      // |swap_promise| must remain active, so place it to |new_swap_promises|
+      // in order to keep it alive.
+      new_swap_promises->push_back(std::move(swap_promise));
+    }
+  }
   swap_promise_list_.clear();
-  swap_promise_list_.swap(*new_swap_promise);
+  swap_promise_list_.swap(*new_swap_promises);
 }
 
 void LayerTreeImpl::FinishSwapPromises(CompositorFrameMetadata* metadata) {
@@ -1500,9 +1505,16 @@ void LayerTreeImpl::FinishSwapPromises(CompositorFrameMetadata* metadata) {
 }
 
 void LayerTreeImpl::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
-  for (const auto& swap_promise : swap_promise_list_)
-    swap_promise->DidNotSwap(reason);
-  swap_promise_list_.clear();
+  {
+    std::vector<std::unique_ptr<SwapPromise>> persistent_swap_promises;
+    for (auto& swap_promise : swap_promise_list_) {
+      if (swap_promise->DidNotSwap(SwapPromise::SWAP_FAILS)) {

[piman, 2016/08/03 16:38:55]

this should be |reason| instead of |SWAP_FAILS|

[svartmetal, 2016/08/04 14:58:49]

Fixed.

+        persistent_swap_promises.push_back(std::move(swap_promise));
+      }
+    }
+    // |persistent_swap_promises| will remain active even when swap fails.
+    swap_promise_list_.swap(persistent_swap_promises);
+  }
   for (const auto& swap_promise : pinned_swap_promise_list_)
     swap_promise->DidNotSwap(reason);

[piman, 2016/08/03 16:38:55]

Should the logic apply here too?

[svartmetal, 2016/08/04 14:58:48]

I think, it should (to be consistent). But maybe we should reconsider the
concept of pinned swap promises as we have generalized way to create persistent
swap promises...  

   pinned_swap_promise_list_.clear();