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

ui/views/widget/native_widget_mac_unittest.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/widget/native_widget_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #import "base/mac/foundation_util.h"
 #import "base/mac/scoped_nsautorelease_pool.h"
@@ skipping 1358 matching lines @@
   [window setContentSize:NSMakeSize(123, 456)];
   // A "late" frame swap at the old size should do nothing.
   test_api.SimulateFrameSwap(rect.size());
   EXPECT_EQ(1, [window invalidateShadowCount]);
 
   test_api.SimulateFrameSwap(gfx::Size(123, 456));
   EXPECT_EQ(2, [window invalidateShadowCount]);
   test_api.SimulateFrameSwap(gfx::Size(123, 456));
   EXPECT_EQ(2, [window invalidateShadowCount]);
 
+  // Hiding the window does not require shadow invalidation.
+  widget->Hide();
+  test_api.SimulateFrameSwap(gfx::Size(123, 456));
+  EXPECT_EQ(2, [window invalidateShadowCount]);
+
+  // Showing a translucent window after hiding it, should trigger shadow
+  // invalidation.
+  widget->Show();
+  test_api.SimulateFrameSwap(gfx::Size(123, 456));
+  EXPECT_EQ(3, [window invalidateShadowCount]);
+
   widget->CloseNow();
 }
 
 // Test that the contentView opacity corresponds to the window type.
 TEST_F(NativeWidgetMacTest, ContentOpacity) {
   NativeWidgetMacTestWindow* window;
   Widget::InitParams init_params =
       CreateParams(Widget::InitParams::TYPE_WINDOW_FRAMELESS);
 
   EXPECT_EQ(init_params.opacity, Widget::InitParams::INFER_OPACITY);
@@ skipping 393 matching lines @@
 
 - (void)dealloc {
   if (deallocFlag_) {
     DCHECK(!*deallocFlag_);
     *deallocFlag_ = true;
   }
   [super dealloc];
 }
 
 @end