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

content/browser/renderer_host/backing_store_win.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 "content/browser/renderer_host/backing_store_win.h"
 
 #include "base/command_line.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/public/common/content_switches.h"
@@ skipping 125 matching lines @@
   TransportDIB* dib = process->GetTransportDIB(bitmap);
   if (!dib)
     return;
 
   BITMAPINFOHEADER hdr;
   gfx::CreateBitmapHeader(bitmap_rect.width(), bitmap_rect.height(), &hdr);
   // Account for a bitmap_rect that exceeds the bounds of our view
   gfx::Rect view_rect(size());
 
   for (size_t i = 0; i < copy_rects.size(); i++) {
-    gfx::Rect paint_rect = view_rect.Intersect(copy_rects[i]);
+    gfx::Rect paint_rect = view_rect;
+    paint_rect.Intersect(copy_rects[i]);
     CallStretchDIBits(hdc_,
                       paint_rect.x(),
                       paint_rect.y(),
                       paint_rect.width(),
                       paint_rect.height(),
                       paint_rect.x() - bitmap_rect.x(),
                       paint_rect.y() - bitmap_rect.y(),
                       paint_rect.width(),
                       paint_rect.height(),
                       dib->memory(),
@@ skipping 16 matching lines @@
                                          const gfx::Rect& clip_rect,
                                          const gfx::Size& view_size) {
   RECT damaged_rect, r = clip_rect.ToRECT();
   ScrollDC(hdc_, dx, dy, NULL, &r, NULL, &damaged_rect);
 
   // TODO(darin): this doesn't work if dx and dy are both non-zero!
   DCHECK(dx == 0 || dy == 0);
 }
 
 }  // namespace content