Change GetAllDisplays() in all screens to return a const vector&.

chrome/browser/ui/window_sizer/window_sizer_common_unittest.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/window_sizer/window_sizer_common_unittest.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "ash/common/wm/window_resizer.h"
@@ skipping 40 matching lines @@
     return false;
   }
 
   gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override {
     NOTREACHED();
     return NULL;
   }
 
   int GetNumDisplays() const override { return displays_.size(); }
 
-  std::vector<display::Display> GetAllDisplays() const override {
+  const std::vector<display::Display>& GetAllDisplays() const override {
     return displays_;
   }
 
   display::Display GetDisplayNearestWindow(
       gfx::NativeView view) const override {
 #if defined(USE_AURA)
     return displays_[index_of_display_nearest_window_];
 #else
     NOTREACHED();
     return display::Display();
@@ skipping 394 matching lines @@
   { // Check that a window which hangs out of the screen get moved back in.
     gfx::Rect window_bounds;
     GetWindowBounds(p1024x768, p1024x768, gfx::Rect(), gfx::Rect(),
                     gfx::Rect(), DEFAULT, NULL,
                     gfx::Rect(1020, 700, 100, 100), &window_bounds);
     EXPECT_EQ("924,668 100x100", window_bounds.ToString());
   }
 }
 
 #endif // defined(OS_MACOSX)