Warn on missing OVERRIDE/virtual everywhere, not just in header files.

ash/wm/partial_screenshot_view_unittest.cc

 // Copyright (c) 2013 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 "ash/wm/partial_screenshot_view.h"
 
 #include "ash/screenshot_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/test/ash_test_base.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/test/event_generator.h"
 
 namespace ash {
 
 class FakeScreenshotDelegate : public ScreenshotDelegate {
  public:
   FakeScreenshotDelegate() : screenshot_count_(0) {}
 
-  void HandleTakeScreenshotForAllRootWindows() OVERRIDE {}
-  void HandleTakePartialScreenshot(aura::Window* window,
-                                   const gfx::Rect& rect) OVERRIDE {
+  virtual void HandleTakeScreenshotForAllRootWindows() OVERRIDE {}
+  virtual void HandleTakePartialScreenshot(aura::Window* window,
+                                           const gfx::Rect& rect) OVERRIDE {
     rect_ = rect;
     screenshot_count_++;
   }
 
-  bool CanTakeScreenshot() OVERRIDE {
+  virtual bool CanTakeScreenshot() OVERRIDE {
     return true;
   }
 
   const gfx::Rect& rect() const { return rect_; };
   int screenshot_count() const { return screenshot_count_; };
 
  private:
   gfx::Rect rect_;
   int screenshot_count_;
 
@@ skipping 56 matching lines @@
   EXPECT_TRUE(view_->is_dragging_);
   EXPECT_EQ("200,200", view_->current_position_.ToString());
 
   generator.ReleaseTouch();
   EXPECT_FALSE(view_->is_dragging_);
   EXPECT_EQ(1, delegate_->screenshot_count());
   EXPECT_EQ("100,100 100x100", delegate_->rect().ToString());
 }
 
 }  // namespace ash