Make gfx::Rect class operations consistently mutate the class they are called on.

ui/gfx/screen_gtk.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 "ui/gfx/screen.h"
 
 #include <gdk/gdkx.h>
 #include <gtk/gtk.h>
 
 #include "base/logging.h"
@@ skipping 123 matching lines @@
   return GetPrimaryDisplay();
 }
 
 // static
 gfx::Display Screen::GetPrimaryDisplay() {
   gfx::Rect bounds = NativePrimaryMonitorBounds();
   // TODO(oshima): Implement ID and Observer.
   gfx::Display display(0, bounds);
   gfx::Rect rect;
   if (GetScreenWorkArea(&rect)) {
-    display.set_work_area(rect.Intersect(bounds));
+    rect.Intersect(bounds);
+    display.set_work_area(rect);
   } else {
     // Return the best we've got.
     display.set_work_area(bounds);
   }
   return display;
 }
 
 // static
 int Screen::GetNumDisplays() {
   // This query is kinda bogus for Linux -- do we want number of X screens?
   // The number of monitors Xinerama has?  We'll just use whatever GDK uses.
   GdkScreen* screen = gdk_screen_get_default();
   return gdk_screen_get_n_monitors(screen);
 }
 
 }  // namespace gfx