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

content/browser/renderer_host/render_widget_host_view_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 "content/browser/renderer_host/render_widget_host_view_gtk.h"
 
 // If this gets included after the gtk headers, then a bunch of compiler
 // errors happen because of a "#define Status int" in Xlib.h, which interacts
 // badly with net::URLRequestStatus::Status.
 #include "content/common/view_messages.h"
@@ skipping 840 matching lines @@
     const std::vector<gfx::Rect>& copy_rects) {
   TRACE_EVENT0("ui::gtk", "RenderWidgetHostViewGtk::DidUpdateBackingStore");
 
   if (is_hidden_)
     return;
 
   // TODO(darin): Implement the equivalent of Win32's ScrollWindowEX.  Can that
   // be done using XCopyArea?  Perhaps similar to
   // BackingStore::ScrollBackingStore?
   if (about_to_validate_and_paint_)
-    invalid_rect_ = invalid_rect_.Union(scroll_rect);
+    invalid_rect_.Union(scroll_rect);
   else
     Paint(scroll_rect);
 
   for (size_t i = 0; i < copy_rects.size(); ++i) {
     // Avoid double painting.  NOTE: This is only relevant given the call to
     // Paint(scroll_rect) above.
-    gfx::Rect rect = copy_rects[i].Subtract(scroll_rect);
+    gfx::Rect rect = copy_rects[i];
+    rect.Subtract(scroll_rect);
     if (rect.IsEmpty())
       continue;
 
     if (about_to_validate_and_paint_)
-      invalid_rect_ = invalid_rect_.Union(rect);
+      invalid_rect_.Union(rect);
     else
       Paint(rect);
   }
 }
 
 void RenderWidgetHostViewGtk::RenderViewGone(base::TerminationStatus status,
                                              int error_code) {
   Destroy();
   plugin_container_manager_.set_host_widget(NULL);
 }
@@ skipping 77 matching lines @@
   GtkClipboard* x_clipboard = gtk_clipboard_get(GDK_SELECTION_PRIMARY);
   gtk_clipboard_set_text(
       x_clipboard, utf8_selection.c_str(), utf8_selection.length());
 }
 
 void RenderWidgetHostViewGtk::SelectionBoundsChanged(
     const gfx::Rect& start_rect,
     WebKit::WebTextDirection start_direction,
     const gfx::Rect& end_rect,
     WebKit::WebTextDirection end_direction) {
-  im_context_->UpdateCaretBounds(start_rect.Union(end_rect));
+  gfx::Rect combined_rect = start_rect;
+  combined_rect.Union(end_rect);
+  im_context_->UpdateCaretBounds(combined_rect);
 }
 
 GdkEventButton* RenderWidgetHostViewGtk::GetLastMouseDown() {
   return last_mouse_down_;
 }
 
 gfx::NativeView RenderWidgetHostViewGtk::BuildInputMethodsGtkMenu() {
   return im_context_->BuildInputMethodsGtkMenu();
 }
 
@@ skipping 186 matching lines @@
 
   // If the size of our canvas is (0,0), then we don't want to block here. We
   // are doing one of our first paints and probably have animations going on.
   bool force_create = !host_->empty();
   BackingStoreGtk* backing_store = static_cast<BackingStoreGtk*>(
       host_->GetBackingStore(force_create));
   // Calling GetBackingStore maybe have changed |invalid_rect_|...
   about_to_validate_and_paint_ = false;
 
   gfx::Rect paint_rect = gfx::Rect(0, 0, kMaxWindowWidth, kMaxWindowHeight);
-  paint_rect = paint_rect.Intersect(invalid_rect_);
+  paint_rect.Intersect(invalid_rect_);
 
   if (backing_store) {
     // Only render the widget if it is attached to a window; there's a short
     // period where this object isn't attached to a window but hasn't been
     // Destroy()ed yet and it receives paint messages...
     if (window) {
       backing_store->XShowRect(gfx::Point(0, 0),
           paint_rect, ui::GetX11WindowFromGtkWidget(view_.get()));
     }
     if (!whiteout_start_time_.is_null()) {
@@ skipping 358 matching lines @@
             this));
   }
   BrowserAccessibilityGtk* root =
       browser_accessibility_manager_->GetRoot()->ToBrowserAccessibilityGtk();
 
   atk_object_set_role(root->GetAtkObject(), ATK_ROLE_HTML_CONTAINER);
   return root->GetAtkObject();
 }
 
 }  // namespace content