mus/aura: Fix setting up LayerTreeFrameSink for a window.

Make sure the LayerTreeFrameSink has the LocalSurfaceId correctly set,
even if the LocalSurfaceId is generated before a LayerTreeFrameSink is
created.

BUG=786453

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I768f06ab84ede54218afd2f9c3dbaf8bbb27296a
Reviewed-on: https://chromium-review.googlesource.com/817632
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523206}

components/viz/client/client_layer_tree_frame_sink.h

@@ -75,6 +75,8 @@ class VIZ_CLIENT_EXPORT ClientLayerTreeFrameSink
     return hit_test_data_provider_.get();
   }
 
+  const LocalSurfaceId& local_surface_id() const { return local_surface_id_; }
+
   // cc::LayerTreeFrameSink implementation.
   bool BindToClient(cc::LayerTreeFrameSinkClient* client) override;
   void DetachFromClient() override;

ui/aura/BUILD.gn

@@ -364,6 +364,7 @@ test("aura_unittests") {
     "mus/os_exchange_data_provider_mus_unittest.cc",
     "mus/property_converter_unittest.cc",
     "mus/user_activity_forwarder_unittest.cc",
+    "mus/window_port_mus_unittest.cc",
     "mus/window_tree_client_unittest.cc",
     "mus/window_tree_host_mus_unittest.cc",
     "test/run_all_unittests.cc",

ui/aura/mus/window_port_mus.cc

@@ -301,14 +301,12 @@ void WindowPortMus::SetFrameSinkIdFromServer(
 
 const viz::LocalSurfaceId& WindowPortMus::GetOrAllocateLocalSurfaceId(
     const gfx::Size& surface_size_in_pixels) {
-  if (last_surface_size_in_pixels_ == surface_size_in_pixels &&
-      local_surface_id_.is_valid()) {
-    return local_surface_id_;
+  if (last_surface_size_in_pixels_ != surface_size_in_pixels ||
+      !local_surface_id_.is_valid()) {
+    local_surface_id_ = parent_local_surface_id_allocator_.GenerateId();
+    last_surface_size_in_pixels_ = surface_size_in_pixels;
   }
 
-  local_surface_id_ = parent_local_surface_id_allocator_.GenerateId();
-  last_surface_size_in_pixels_ = surface_size_in_pixels;
-
   // If the FrameSinkId is available, then immediately embed the SurfaceId.
   // The newly generated frame by the embedder will block in the display
   // compositor until the child submits a corresponding CompositorFrame or a

ui/aura/mus/window_port_mus.h

@@ -37,7 +37,7 @@ namespace aura {
 class ClientSurfaceEmbedder;
 class PropertyConverter;
 class Window;
-class WindowPortMusTestApi;
+class WindowPortMusTest;
 class WindowTreeClient;
 class WindowTreeClientPrivate;
 class WindowTreeHostMus;
@@ -99,7 +99,7 @@ class AURA_EXPORT WindowPortMus : public WindowPort, public WindowMus {
   viz::FrameSinkId GetFrameSinkId() const override;
 
  private:
-  friend class WindowPortMusTestApi;
+  friend class WindowPortMusTest;
   friend class WindowTreeClient;
   friend class WindowTreeClientPrivate;
   friend class WindowTreeHostMus;

ui/aura/mus/window_port_mus_unittest.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/aura/mus/window_port_mus.h"
+
+#include "components/viz/client/client_layer_tree_frame_sink.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/aura/test/aura_test_base.h"
+#include "ui/aura/window.h"
+
+namespace aura {
+
+class WindowPortMusTest : public test::AuraTestBase {
+ public:
+  WindowPortMusTest() { EnableMusWithTestWindowTree(); }
+
+  ~WindowPortMusTest() override = default;
+
+  base::WeakPtr<viz::ClientLayerTreeFrameSink> GetFrameSinkFor(Window* window) {
+    auto* window_mus = WindowPortMus::Get(window);
+    return window_mus->local_layer_tree_frame_sink_;
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WindowPortMusTest);
+};
+
+TEST_F(WindowPortMusTest, LayerTreeFrameSinkGetsCorrectLocalSurfaceId) {
+  Window window(nullptr);
+  window.Init(ui::LAYER_NOT_DRAWN);
+  window.SetBounds(gfx::Rect(300, 300));
+  // Notify the window that it will embed an external client, so that it
+  // correctly generates LocalSurfaceId.
+  window.set_embed_frame_sink_id(viz::FrameSinkId(0, 1));
+
+  viz::LocalSurfaceId local_surface_id = window.GetLocalSurfaceId();
+  ASSERT_TRUE(local_surface_id.is_valid());
+
+  std::unique_ptr<cc::LayerTreeFrameSink> frame_sink(
+      window.CreateLayerTreeFrameSink());
+  EXPECT_TRUE(frame_sink.get());
+
+  auto mus_frame_sink = GetFrameSinkFor(&window);
+  ASSERT_TRUE(mus_frame_sink);
+  EXPECT_TRUE(mus_frame_sink->local_surface_id().is_valid());
+  EXPECT_EQ(mus_frame_sink->local_surface_id(), local_surface_id);
+}
+
+}  // namespace aura