MacViews: Don't draw blank windows after de-miniturize

Whenever the ui::Layer for BridgedNativeWidgetMac is hidden, also lock
the ui::Compositor ("lock" in this sense means "disable drawing new
frames").

This ensure that we won't draw any blank frames (which is what would
result in a blank frame).

Bug: 712244
Change-Id: Ia8c17742e6a48190b9a3aead6443102a585d1f7d
Reviewed-on: https://chromium-review.googlesource.com/1129320
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574187}

ui/views/cocoa/bridged_native_widget.h

@@ -287,6 +287,11 @@ class VIEWS_EXPORT BridgedNativeWidget
   // DialogObserver:
   void OnDialogModelChanged() override;
 
+  // Set |layer()| to be visible or not visible based on |window_visible_|. If
+  // the layer is not visible, then lock the compositor, so we don't draw any
+  // new frames.
+  void UpdateLayerVisibility();
+
   views::NativeWidgetMac* native_widget_mac_;  // Weak. Owns this.
   base::scoped_nsobject<NSWindow> window_;
   base::scoped_nsobject<ViewsNSWindowDelegate> window_delegate_;
@@ -307,6 +312,8 @@ class VIEWS_EXPORT BridgedNativeWidget
   std::unique_ptr<ui::AcceleratedWidgetMac> compositor_widget_;
   std::unique_ptr<ui::DisplayCALayerTree> display_ca_layer_tree_;
   std::unique_ptr<ui::Compositor> compositor_;
+  std::unique_ptr<ui::CompositorLock> compositor_lock_;
+
   viz::ParentLocalSurfaceIdAllocator parent_local_surface_id_allocator_;
 
   // Tracks the bounds when the window last started entering fullscreen. Used to

ui/views/cocoa/bridged_native_widget.mm

@@ -796,12 +796,11 @@ void BridgedNativeWidget::OnVisibilityChanged() {
   // TODO(tapted): Investigate whether we want this for Mac. This is what Aura
   // does, and it is what tests expect. However, because layer drawing is
   // asynchronous (and things like deminiaturize in AppKit are not), it can
-  // result in a CALayer appearing on screen before it has been redrawn in the
-  // GPU process. This is a general problem. In content, a helper class,
-  // RenderWidgetResizeHelper, blocks the UI thread in -[NSView setFrameSize:]
-  // and RenderWidgetHostView::Show() until a frame is ready.
+  // result in the compositor producing a blank frame during the time that the
+  // layer is not visible. Avoid this by locking the compositor (preventing any
+  // new frames) in UpdateLayerVisibility whenever the layer is hidden.
   if (layer()) {
-    layer()->SetVisible(window_visible_);
+    UpdateLayerVisibility();
     layer()->SchedulePaint(gfx::Rect(GetClientAreaSize()));
 
     // For translucent windows which are made visible, recalculate shadow when
@@ -904,7 +903,7 @@ void BridgedNativeWidget::CreateLayer(ui::LayerType layer_type,
   SetLayer(std::make_unique<ui::Layer>(layer_type));
   // Note, except for controls, this will set the layer to be hidden, since it
   // is only called during Init().
-  layer()->SetVisible(window_visible_);
+  UpdateLayerVisibility();
   layer()->set_delegate(this);
 
   InitCompositor();
@@ -1347,7 +1346,7 @@ void BridgedNativeWidget::ShowAsModalSheet() {
   // So that it doesn't animate a fully transparent window, first wait for a
   // frame. The first step is to pretend that the window is already visible.
   window_visible_ = true;
-  layer()->SetVisible(true);
+  UpdateLayerVisibility();
   native_widget_mac_->GetWidget()->OnNativeWidgetVisibilityChanged(true);
   MaybeWaitForFrame(GetClientAreaSize());
 
@@ -1376,4 +1375,16 @@ NSMutableDictionary* BridgedNativeWidget::GetWindowProperties() const {
   return properties;
 }
 
+void BridgedNativeWidget::UpdateLayerVisibility() {
+  layer()->SetVisible(window_visible_);
+  if (window_visible_) {
+    compositor_lock_.reset();
+  } else if (!compositor_lock_) {
+    // Assume that GetCompositorLock always succeeds (if it does not, then a
+    // flicker may be seen).
+    compositor_lock_ =
+        compositor_->GetCompositorLock(nullptr, base::TimeDelta());
+  }
+}
+
 }  // namespace views