[cc] Set BeginFrame sequence numbers on CompositorFrames from Scheduler.

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 e5f4583ee5986b2ebb5ecd698c891a3405e141bf..96a04ac369abab0d8b38376562eb368755e3715d 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -34,6 +34,7 @@
 #include "cc/quads/render_pass_draw_quad.h"
 #include "cc/quads/tile_draw_quad.h"
 #include "cc/resources/ui_resource_manager.h"
+#include "cc/test/begin_frame_args_test.h"
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_layer_tree_host_client.h"
 #include "cc/test/fake_output_surface.h"
@@ -7007,5 +7008,78 @@ class LayerTreeHostTestSubmitFrameResources : public LayerTreeHostTest {
 
 SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostTestSubmitFrameResources);
 
+class LayerTreeHostTestBeginFrameSequenceNumbers : public LayerTreeHostTest {
+ protected:
+  void BeginTest() override { PostSetNeedsCommitToMainThread(); }
+
+  void WillBeginImplFrameOnThread(LayerTreeHostImpl* impl,
+                                  const BeginFrameArgs& args) override {
+    // First BeginFrame will block activation, second one unblocks.
+    impl->BlockNotifyReadyToActivateForTesting(false);
+
+    EXPECT_TRUE(args.IsValid());
+    current_begin_frame_args_ = args;
+  }
+
+  void BeginMainFrame(const BeginFrameArgs& args) override {
+    EXPECT_TRUE(args.IsValid());
+    if (!current_begin_main_frame_args_.IsValid())
+      current_begin_main_frame_args_ = args;

[brianderson, 2017/03/02 19:53:36]

current_begin_main_frame_args_ is written on the main thread here and read on
the impl thread from *OnThread methods without a lock, which might result in a
corrupt view and a flaky test.

BeginCommitOnThread occurs while the main thread and impl threads are "locked",
so you can safely transfer the value to the impl thread from that hook.

[Eric Seckler, 2017/03/07 12:26:56]

Ah, I see. Added a copy to impl.

+  }
+
+  void BeginCommitOnThread(LayerTreeHostImpl* impl) override {
+    // Request another subsequent commit. That way, the first commit's
+    // latest_confirmed_sequence_number should stay at the first BeginFrame's
+    // sequence number.
+    PostSetNeedsCommitToMainThread();
+  }
+
+  void WillCommitCompleteOnThread(LayerTreeHostImpl* impl) override {
+    // Defer current commit's activation until second BeginFrame.
+    impl->BlockNotifyReadyToActivateForTesting(true);
+  }
+
+  DrawResult PrepareToDrawOnThread(LayerTreeHostImpl* impl,
+                                   LayerTreeHostImpl::FrameData* frame_data,
+                                   DrawResult draw_result) override {
+    // We should only draw in second BeginFrame.
+    EXPECT_TRUE(current_begin_main_frame_args_.IsValid());
+    EXPECT_LT(current_begin_main_frame_args_.sequence_number,
+              current_begin_frame_args_.sequence_number);
+    frame_data_ = frame_data;
+    return draw_result;
+  }
+
+  void DrawLayersOnThread(LayerTreeHostImpl* impl) override {
+    EXPECT_TRUE(frame_data_);
+    EXPECT_EQ(
+        BeginFrameAck(current_begin_frame_args_.source_id,
+                      current_begin_frame_args_.sequence_number,
+                      current_begin_main_frame_args_.sequence_number, 0, true),
+        frame_data_->begin_frame_ack);
+  }
+
+  void DisplayReceivedCompositorFrameOnThread(
+      const CompositorFrame& frame) override {
+    compositor_frame_submitted_ = true;
+    EXPECT_EQ(
+        BeginFrameAck(current_begin_frame_args_.source_id,
+                      current_begin_frame_args_.sequence_number,
+                      current_begin_main_frame_args_.sequence_number, 0, true),
+        frame.metadata.begin_frame_ack);
+    EndTest();
+  }
+
+  void AfterTest() override { EXPECT_TRUE(compositor_frame_submitted_); }
+
+ private:
+  bool compositor_frame_submitted_;
+  BeginFrameArgs current_begin_frame_args_;
+  BeginFrameArgs current_begin_main_frame_args_;
+  LayerTreeHostImpl::FrameData* frame_data_;
+};
+
+MULTI_THREAD_BLOCKNOTIFY_TEST_F(LayerTreeHostTestBeginFrameSequenceNumbers);
+
 }  // namespace
 }  // namespace cc