Close the screenshot flash effect before the screenshot task is actually executed.

chrome/browser/ui/views/ash/screenshot_taker.cc

 // Copyright (c) 2012 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 "chrome/browser/ui/views/ash/screenshot_taker.h"
 
 #include <string>
 
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ skipping 99 matching lines @@
       rect,
       base::Bind(&TakeScreenshot, base::Unretained(window), rect));
 }
 
 void ScreenshotTaker::HandleTakeScreenshot(aura::Window* window) {
   HandleTakePartialScreenshot(window, window->bounds());
 }
 
 void ScreenshotTaker::CloseVisualFeedbackLayer(const base::Closure& task) {
   visual_feedback_layer_.reset();
-  task.Run();
+  // Hide the visual feedback immediately because |task| may take a long time
+  // to finish.
+  MessageLoopForUI::current()->PostTask(FROM_HERE, task);
 }
 
 void ScreenshotTaker::DisplayVisualFeedback(const gfx::Rect& rect,
                                             const base::Closure& task) {
   visual_feedback_layer_.reset(new ui::Layer(ui::LAYER_SOLID_COLOR));
   visual_feedback_layer_->SetColor(SK_ColorWHITE);
   visual_feedback_layer_->SetOpacity(kVisualFeedbackLayerOpacity);
   visual_feedback_layer_->SetBounds(rect);
 
   ui::Layer* parent = ash::Shell::GetInstance()->GetContainer(
       ash::internal::kShellWindowId_OverlayContainer)->layer();
   parent->Add(visual_feedback_layer_.get());
   visual_feedback_layer_->SetVisible(true);
 
   MessageLoopForUI::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&ScreenshotTaker::CloseVisualFeedbackLayer,
                  base::Unretained(this),
                  task),
       base::TimeDelta::FromMilliseconds(kVisualFeedbackLayerDisplayTimeMs));
 }