Add non-member non-mutating methods for common gfx::Rect operations.

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 847 matching lines @@
   // be done using XCopyArea?  Perhaps similar to
   // BackingStore::ScrollBackingStore?
   if (about_to_validate_and_paint_)
     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];
-    rect.Subtract(scroll_rect);
+    gfx::Rect rect = gfx::Subtraction(copy_rects[i], scroll_rect);
     if (rect.IsEmpty())
       continue;
 
     if (about_to_validate_and_paint_)
       invalid_rect_.Union(rect);
     else
       Paint(rect);
   }
 }
 
@@ skipping 82 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) {
-  gfx::Rect combined_rect = start_rect;
-  combined_rect.Union(end_rect);
-  im_context_->UpdateCaretBounds(combined_rect);
+  im_context_->UpdateCaretBounds(gfx::Union(start_rect, end_rect));
 }
 
 GdkEventButton* RenderWidgetHostViewGtk::GetLastMouseDown() {
   return last_mouse_down_;
 }
 
 gfx::NativeView RenderWidgetHostViewGtk::BuildInputMethodsGtkMenu() {
   return im_context_->BuildInputMethodsGtkMenu();
 }
 
@@ skipping 565 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