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

webkit/tools/test_shell/webwidget_host_gtk.cc

 // Copyright (c) 2011 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 "webkit/tools/test_shell/webwidget_host.h"
 
 #include <cairo/cairo.h>
 #include <gtk/gtk.h>
 
 #include "base/basictypes.h"
@@ skipping 272 matching lines @@
   host->view_ = CreateWidget(parent_view, host);
   host->webwidget_ = WebPopupMenu::create(client);
   // We manage our own double buffering because we need to be able to update
   // the expose area in an ExposeEvent within the lifetime of the event handler.
   gtk_widget_set_double_buffered(GTK_WIDGET(host->view_), false);
 
   return host;
 }
 
 void WebWidgetHost::UpdatePaintRect(const gfx::Rect& rect) {
-  paint_rect_ = paint_rect_.Union(rect);
+  paint_rect_.Union(rect);
 }
 
 void WebWidgetHost::DidInvalidateRect(const gfx::Rect& damaged_rect) {
   DLOG_IF(WARNING, painting_) << "unexpected invalidation while painting";
 
   UpdatePaintRect(damaged_rect);
 
   if (!g_handling_expose) {
     gtk_widget_queue_draw_area(GTK_WIDGET(view_), damaged_rect.x(),
         damaged_rect.y(), damaged_rect.width(), damaged_rect.height());
@@ skipping 66 matching lines @@
   // This may result in more invalidation
   webwidget_->layout();
 
   // Paint the canvas if necessary.  Allow painting to generate extra rects the
   // first time we call it.  This is necessary because some WebCore rendering
   // objects update their layout only when painted.
   // Store the total area painted in total_paint. Then tell the gdk window
   // to update that area after we're done painting it.
   gfx::Rect total_paint;
   for (int i = 0; i < 2; ++i) {
-    paint_rect_ = client_rect.Intersect(paint_rect_);
+    paint_rect_.Intersect(client_rect);
     if (!paint_rect_.IsEmpty()) {
       gfx::Rect rect(paint_rect_);
       paint_rect_ = gfx::Rect();
 
       DLOG_IF(WARNING, i == 1) << "painting caused additional invalidations";
       PaintRect(rect);
-      total_paint = total_paint.Union(rect);
+      total_paint.Union(rect);
     }
   }
   //DCHECK(paint_rect_.IsEmpty());
 
   // Invalidate the paint region on the widget's underlying gdk window. Note
   // that gdk_window_invalidate_* will generate extra expose events, which
   // we wish to avoid. So instead we use calls to begin_paint/end_paint.
   GdkRectangle grect = {
       total_paint.x(),
       total_paint.y(),
@@ skipping 28 matching lines @@
 
 void WebWidgetHost::PaintRect(const gfx::Rect& rect) {
   set_painting(true);
   webwidget_->paint(canvas_.get(), rect);
   set_painting(false);
 }
 
 void WebWidgetHost::WindowDestroyed() {
   delete this;
 }