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..d3bb71896ee419289e06694ae27735f0994a0387 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1483,11 +1483,17 @@ 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) ==
+        SwapPromise::DidNotSwapAction::KEEP_ACTIVE) {
+      // |swap_promise| must remain active, so place it to |new_swap_promises|

[danakj, 2016/08/10 01:04:15]

"place it in"

[svartmetal, 2016/08/10 17:38:22]

Done.

+      // in order to keep it alive and active.
+      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) {
@@ -1500,12 +1506,30 @@ 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();
-  for (const auto& swap_promise : pinned_swap_promise_list_)
-    swap_promise->DidNotSwap(reason);
-  pinned_swap_promise_list_.clear();
+  {
+    std::vector<std::unique_ptr<SwapPromise>> persistent_swap_promises;
+    for (auto& swap_promise : swap_promise_list_) {
+      if (swap_promise->DidNotSwap(reason) ==
+          SwapPromise::DidNotSwapAction::KEEP_ACTIVE) {
+        persistent_swap_promises.push_back(std::move(swap_promise));
+      }
+    }
+    // |persistent_swap_promises| must remain active even when swap fails.
+    swap_promise_list_.swap(persistent_swap_promises);

[danakj, 2016/08/10 01:04:15]

nit: swap_promise_list_ = std::move(persistent_swap_promises) cuz we don't
actually care what ends up in persistent_swap_promises.

[svartmetal, 2016/08/10 17:38:22]

Done.

+  }
+
+  {
+    std::vector<std::unique_ptr<SwapPromise>> persistent_swap_promises;
+    for (auto& swap_promise : pinned_swap_promise_list_) {
+      if (swap_promise->DidNotSwap(reason) ==
+          SwapPromise::DidNotSwapAction::KEEP_ACTIVE) {
+        persistent_swap_promises.push_back(std::move(swap_promise));
+      }
+    }
+
+    // |persistent_swap_promises| must remain active even when swap fails.
+    pinned_swap_promise_list_.swap(persistent_swap_promises);

[danakj, 2016/08/10 01:04:15]

ditto

[svartmetal, 2016/08/10 17:38:21]

Done.

+  }
 }
 
 void LayerTreeImpl::DidModifyTilePriorities() {