MacViews: Trigger shadow invalidation when a translucent window is shown.

ui/views/cocoa/bridged_native_widget.mm

 // Copyright 2014 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.
 
 #import "ui/views/cocoa/bridged_native_widget.h"
 
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 821 matching lines @@
   // 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.
   if (layer()) {
     layer()->SetVisible(window_visible_);
     layer()->SchedulePaint(gfx::Rect(GetClientAreaSize()));
+
+    // For translucent windows which are made visible, recalculate shadow when
+    // the frame from the compositor arrives.
+    if (![window_ isOpaque])
+      invalidate_shadow_on_frame_swap_ = window_visible_;
   }
 
   NotifyVisibilityChangeDown();
 
   native_widget_mac_->GetWidget()->OnNativeWidgetVisibilityChanged(
       window_visible_);
 
   // Toolkit-views suppresses redraws while not visible. To prevent Cocoa asking
   // for an "empty" draw, disable auto-display while hidden. For example, this
   // prevents Cocoa drawing just *after* a minimize, resulting in a blank window
@@ skipping 532 matching lines @@
   [bridged_view_ setMouseDownCanMoveWindow:draggable];
   // AppKit will not update its cache of mouseDownCanMoveWindow unless something
   // changes. Previously we tried adding an NSView and removing it, but for some
   // reason it required reposting the mouse-down event, and didn't always work.
   // Calling the below seems to be an effective solution.
   [window_ setMovableByWindowBackground:NO];
   [window_ setMovableByWindowBackground:YES];
 }
 
 }  // namespace views