Add black layer on the back of wallpaper

Apply layer blur on the layer that has wallpaper, but not the widget
because the solid color is a part of widget's layer.

Bug: 1015886
Test: covered by unittest. Also tested manually with blur change reverted.
Change-Id: Iaf0f2faaa1e92285a3f8b45083027a7fccf0bc59
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1885219Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710141}

ash/display/root_window_transformers_unittest.cc

@@ -40,7 +40,7 @@
 namespace ash {
 namespace {
 
-const char kWallpaperView[] = "WallpaperView";
+const char kWallpaperView[] = "WallpaperViewWidget";
 
 class TestEventHandler : public ui::EventHandler {
  public:

ash/display/window_tree_host_manager_unittest.cc

@@ -50,7 +50,7 @@
 namespace ash {
 namespace {
 
-const char kWallpaperView[] = "WallpaperView";
+const char kWallpaperView[] = "WallpaperViewWidget";
 
 template <typename T>
 class Resetter {

ash/wallpaper/wallpaper_controller_unittest.cc

@@ -1913,11 +1913,23 @@ TEST_F(WallpaperControllerTest, WallpaperBlur) {
 }
 
 TEST_F(WallpaperControllerTest, WallpaperBlurDuringLockScreenTransition) {
+  ui::ScopedAnimationDurationScaleMode test_duration_mode(
+      ui::ScopedAnimationDurationScaleMode::NON_ZERO_DURATION);
+
+  gfx::ImageSkia image = CreateImage(600, 400, kWallpaperColor);
+  controller_->ShowWallpaperImage(
+      image, CreateWallpaperInfo(WALLPAPER_LAYOUT_CENTER),
+      /*preview_mode=*/false, /*always_on_top=*/false);
+
   TestWallpaperControllerObserver observer(controller_);
 
   ASSERT_TRUE(controller_->IsBlurAllowed());
   ASSERT_FALSE(controller_->IsWallpaperBlurred());
 
+  ASSERT_EQ(1u, wallpaper_view()->layer()->parent()->children().size());
+  EXPECT_EQ(ui::LAYER_TEXTURED,
+            wallpaper_view()->layer()->parent()->children()[0]->type());
+
   // Simulate lock and unlock sequence.
   controller_->UpdateWallpaperBlur(true);
   EXPECT_TRUE(controller_->IsWallpaperBlurred());
@@ -1925,12 +1937,20 @@ TEST_F(WallpaperControllerTest, WallpaperBlurDuringLockScreenTransition) {
 
   SetSessionState(SessionState::LOCKED);
   EXPECT_TRUE(controller_->IsWallpaperBlurred());
+  ASSERT_EQ(2u, wallpaper_view()->layer()->parent()->children().size());
+  EXPECT_EQ(ui::LAYER_SOLID_COLOR,
+            wallpaper_view()->layer()->parent()->children()[0]->type());
+  EXPECT_EQ(ui::LAYER_TEXTURED,
+            wallpaper_view()->layer()->parent()->children()[1]->type());
 
   // Change of state to ACTIVE triggers post lock animation and
   // UpdateWallpaperBlur(false)
   SetSessionState(SessionState::ACTIVE);
   EXPECT_FALSE(controller_->IsWallpaperBlurred());
   EXPECT_EQ(2, observer.blur_changed_count());
+  ASSERT_EQ(1u, wallpaper_view()->layer()->parent()->children().size());
+  EXPECT_EQ(ui::LAYER_TEXTURED,
+            wallpaper_view()->layer()->parent()->children()[0]->type());
 }
 
 TEST_F(WallpaperControllerTest, OnlyShowDevicePolicyWallpaperOnLoginScreen) {

ash/wallpaper/wallpaper_view.cc

@@ -34,7 +34,14 @@ namespace {
 // in the compositor.
 class LayerControlView : public views::View {
  public:
-  explicit LayerControlView(views::View* view) {
+  LayerControlView(views::View* view, bool needs_shield) {
+    if (needs_shield) {
+      auto* shield = new views::View();
+      AddChildView(shield);
+      shield->SetPaintToLayer(ui::LAYER_SOLID_COLOR);
+      shield->layer()->SetColor(SK_ColorBLACK);
+      shield->layer()->set_name("WallpaperViewShield");
+    }
     AddChildView(view);
     view->SetPaintToLayer();
   }
@@ -51,14 +58,15 @@ class LayerControlView : public views::View {
     display::ManagedDisplayInfo info =
         Shell::Get()->display_manager()->GetDisplayInfo(display.id());
 
-    DCHECK_EQ(1u, children().size());
-    views::View* child = children().front();
-    child->SetBounds(0, 0, display.size().width(), display.size().height());
-    gfx::Transform transform;
-    // Apply RTL transform explicitly becacuse Views layer code
-    // doesn't handle RTL.  crbug.com/458753.
-    transform.Translate(-child->GetMirroredX(), 0);
-    child->SetTransform(transform);
+    for (auto* child : children()) {
+      // views::View* child = children().front();
+      child->SetBounds(0, 0, display.size().width(), display.size().height());
+      gfx::Transform transform;
+      // Apply RTL transform explicitly becacuse Views layer code
+      // doesn't handle RTL.  crbug.com/458753.
+      transform.Translate(-child->GetMirroredX(), 0);
+      child->SetTransform(transform);
+    }
   }
 
  private:
@@ -179,14 +187,17 @@ views::Widget* CreateWallpaperWidget(aura::Window* root_window,
   views::Widget* wallpaper_widget = new views::Widget;
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
-  params.name = "WallpaperView";
+  params.name = "WallpaperViewWidget";
+  params.layer_type = ui::LAYER_NOT_DRAWN;
   if (controller->GetWallpaper().isNull())
     params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
   params.parent = root_window->GetChildById(container_id);
   wallpaper_widget->Init(std::move(params));
   // Owned by views.
   WallpaperView* wallpaper_view = new WallpaperView(blur, opacity);
-  wallpaper_widget->SetContentsView(new LayerControlView(wallpaper_view));
+  wallpaper_widget->SetContentsView(new LayerControlView(
+      wallpaper_view,
+      Shell::Get()->session_controller()->IsUserSessionBlocked()));
   *out_wallpaper_view = wallpaper_view;
   int animation_type =
       controller->ShouldShowInitialAnimation()

ash/wallpaper/wallpaper_widget_controller.cc

@@ -108,7 +108,8 @@ class WallpaperWidgetController::WidgetHandler
   float blur_sigma() const { return widget_->GetLayer()->layer_blur(); }
 
   void SetBlur(float blur_sigma) {
-    widget_->GetLayer()->SetLayerBlur(blur_sigma);
+    wallpaper_view_->layer()->SetLayerBlur(blur_sigma);
+
     const bool old_has_blur_cache = has_blur_cache_;
     has_blur_cache_ = blur_sigma > 0.0f;
     if (!old_has_blur_cache && has_blur_cache_) {