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

ui/views/win/hwnd_message_handler.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/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <shellapi.h>
 
 #include "base/bind.h"
@@ skipping 824 matching lines @@
   // WM_DWMCOMPOSITIONCHANGED is only sent to top level windows, however we want
   // to notify our children too, since we can have MDI child windows who need to
   // update their appearance.
   EnumChildWindows(hwnd(), &SendDwmCompositionChanged, NULL);
 }
 
 void HWNDMessageHandler::SchedulePaintInRect(const gfx::Rect& rect) {
   if (use_layered_buffer_) {
     // We must update the back-buffer immediately, since Windows' handling of
     // invalid rects is somewhat mysterious.
-    invalid_rect_ = invalid_rect_.Union(rect);
+    invalid_rect_.Union(rect);
 
     // In some situations, such as drag and drop, when Windows itself runs a
     // nested message loop our message loop appears to be starved and we don't
     // receive calls to DidProcessMessage(). This only seems to affect layered
     // windows, so we schedule a redraw manually using a task, since those never
     // seem to be starved. Also, wtf.
     if (!paint_layered_window_factory_.HasWeakPtrs()) {
       MessageLoop::current()->PostTask(
           FROM_HERE,
           base::Bind(&HWNDMessageHandler::RedrawLayeredWindowContents,
@@ skipping 1171 matching lines @@
         // response is to throw away the existing position/size information in
         // |window_pos| and recalculate it based on the new work rect.
         gfx::Rect new_window_rect;
         if (fullscreen_handler_->fullscreen()) {
           new_window_rect = monitor_rect;
         } else if (IsMaximized()) {
           new_window_rect = work_area;
           int border_thickness = GetSystemMetrics(SM_CXSIZEFRAME);
           new_window_rect.Inset(-border_thickness, -border_thickness);
         } else {
-          new_window_rect = gfx::Rect(window_rect).AdjustToFit(work_area);
+          new_window_rect = gfx::Rect(window_rect);
+          new_window_rect.AdjustToFit(work_area);
         }
         window_pos->x = new_window_rect.x();
         window_pos->y = new_window_rect.y();
         window_pos->cx = new_window_rect.width();
         window_pos->cy = new_window_rect.height();
         // WARNING!  Don't set SWP_FRAMECHANGED here, it breaks moving the child
         // HWNDs for some reason.
         window_pos->flags &= ~(SWP_NOSIZE | SWP_NOMOVE | SWP_NOREDRAW);
         window_pos->flags |= SWP_NOCOPYBITS;
 
@@ skipping 31 matching lines @@
     DwmExtendFrameIntoClientArea(hwnd(), &m);
   }
   if (window_pos->flags & SWP_SHOWWINDOW)
     delegate_->HandleVisibilityChanged(true);
   else if (window_pos->flags & SWP_HIDEWINDOW)
     delegate_->HandleVisibilityChanged(false);
   SetMsgHandled(FALSE);
 }
 
 }  // namespace views