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

ui/views/view.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/views/view.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 318 matching lines @@
 
   while (view != NULL && !vis_bounds.IsEmpty()) {
     transform.ConcatTransform(view->GetTransform());
     transform.ConcatTranslate(static_cast<float>(view->GetMirroredX()),
                               static_cast<float>(view->y()));
 
     vis_bounds = view->ConvertRectToParent(vis_bounds);
     const View* ancestor = view->parent_;
     if (ancestor != NULL) {
       ancestor_bounds.SetRect(0, 0, ancestor->width(), ancestor->height());
-      vis_bounds = vis_bounds.Intersect(ancestor_bounds);
+      vis_bounds.Intersect(ancestor_bounds);
     } else if (!view->GetWidget()) {
       // If the view has no Widget, we're not visible. Return an empty rect.
       return gfx::Rect();
     }
     view = ancestor;
   }
   if (vis_bounds.IsEmpty())
     return vis_bounds;
   // Convert back to this views coordinate system.
   transform.TransformRectReverse(&vis_bounds);
@@ skipping 1772 matching lines @@
   gfx::Point widget_location(event.location());
   ConvertPointToWidget(this, &widget_location);
   GetWidget()->RunShellDrag(this, data, widget_location, drag_operations);
   return true;
 #else
   return false;
 #endif  // !defined(OS_MACOSX)
 }
 
 }  // namespace views