Use scoped_ptr to document ownership in InstantUnloadHandler.

chrome/browser/ui/browser_instant_controller.cc

 // Copyright 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 "chrome/browser/ui/browser_instant_controller.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/prefs/pref_registry_syncable.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 153 matching lines @@
     ReplaceWebContentsAt(
         browser_->tab_strip_model()->active_index(),
         preview.Pass());
   }
 }
 
 void BrowserInstantController::ReplaceWebContentsAt(
     int index,
     scoped_ptr<content::WebContents> new_contents) {
   DCHECK_NE(TabStripModel::kNoTab, index);
-  content::WebContents* old_contents =
-      browser_->tab_strip_model()->GetWebContentsAt(index);
-  // TabStripModel takes ownership of |new_contents|.
-  browser_->tab_strip_model()->ReplaceWebContentsAt(
-      index, new_contents.release());
-  // TODO(samarth): use scoped_ptr instead of comments to document ownership
-  // transfer.
-  // InstantUnloadHandler takes ownership of |old_contents|.
-  instant_unload_handler_.RunUnloadListenersOrDestroy(old_contents, index);
+  scoped_ptr<content::WebContents> old_contents(browser_->tab_strip_model()->
+      ReplaceWebContentsAt(index, new_contents.release()));
+  instant_unload_handler_.RunUnloadListenersOrDestroy(old_contents.Pass(),
+                                                      index);
 }
 
 void BrowserInstantController::SetInstantSuggestion(
     const InstantSuggestion& suggestion) {
   browser_->window()->GetLocationBar()->SetInstantSuggestion(suggestion);
 }
 
 gfx::Rect BrowserInstantController::GetInstantBounds() {
   return browser_->window()->GetInstantBounds();
 }
@@ skipping 171 matching lines @@
   // part of the image overlay should draw, 'cos the origin is top-left.
   if (!browser_->search_model()->mode().is_ntp() ||
       theme_info_.theme_id.empty() ||
       theme_info_.image_vertical_alignment == THEME_BKGRND_IMAGE_ALIGN_TOP) {
     return;
   }
   instant_.ThemeAreaHeightChanged(theme_area_height_);
 }
 
 }  // namespace chrome