Add comment to GetSourceProfile.

chrome/browser/ui/browser_navigator.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 "chrome/browser/ui/browser_navigator.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 230 matching lines @@
       params->tabstrip_add_types |= TabStripModel::ADD_ACTIVE;
       break;
 
     default:
       break;
   }
 }
 
 // Obtain the profile used by the code that originated the Navigate() request.
 Profile* GetSourceProfile(chrome::NavigateParams* params) {
+  // |source_site_instance| needs to be checked before |source_contents|. This
+  // might matter when chrome.windows.create is used to open multiple URLs,
+  // which would reuse |params| and modify |params->source_contents| across
+  // navigations.
   if (params->source_site_instance) {
     return Profile::FromBrowserContext(
         params->source_site_instance->GetBrowserContext());
   }
 
   if (params->source_contents) {
     return Profile::FromBrowserContext(
         params->source_contents->GetBrowserContext());
   }
 
@@ skipping 409 matching lines @@
   bool reverse_on_redirect = false;
   content::BrowserURLHandler::GetInstance()->RewriteURLIfNecessary(
       &rewritten_url, browser_context, &reverse_on_redirect);
 
   // Some URLs are mapped to uber subpages. Do not allow them in incognito.
   return !(rewritten_url.scheme() == content::kChromeUIScheme &&
            rewritten_url.host() == chrome::kChromeUIUberHost);
 }
 
 }  // namespace chrome