Force extensions to run in their shared processes, even with --process-per-tab.

chrome/browser/browsing_instance.cc

 // Copyright (c) 2006-2008 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/browsing_instance.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/renderer_host/site_instance.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 
 /*static*/
 BrowsingInstance::ProfileSiteInstanceMap
     BrowsingInstance::profile_site_instance_map_;
 
 bool BrowsingInstance::ShouldUseProcessPerSite(const GURL& url) {
   // Returns true if we should use the process-per-site model.  This will be
   // the case if the --process-per-site switch is specified, or in
   // process-per-site-instance for particular sites (e.g., the new tab page).
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kProcessPerSite))
     return true;
+ 
+  if (url.SchemeIs(chrome::kExtensionScheme)) {
+    // Always consolidate extensions regardless of the command line, because
+    // they will break if split into multiple processes.
+    return true;
+  }
 
   if (!command_line.HasSwitch(switches::kProcessPerTab)) {
     // We are not in process-per-site or process-per-tab, so we must be in the
     // default (process-per-site-instance).  Only use the process-per-site
     // logic for particular sites that we want to consolidate.
     // Note that --single-process may have been specified, but that affects the
     // process creation logic in RenderProcessHost, so we do not need to worry
     // about it here.
-    if (url.SchemeIs(chrome::kChromeUIScheme) ||
-        url.SchemeIs(chrome::kExtensionScheme))
+    if (url.SchemeIs(chrome::kChromeUIScheme))
       // Always consolidate instances of the new tab page (and instances of any
-      // other internal resource urls), as well as extensions.
+      // other internal resource urls.
       return true;
 
     // TODO(creis): List any other special cases that we want to limit to a
     // single process for all instances.
   }
 
   // In all other cases, don't use process-per-site logic.
   return false;
 }
 
@@ skipping 64 matching lines @@
   // Only unregister the SiteInstance if it is the same one that is registered
   // for the site.  (It might have been an unregistered SiteInstance.  See the
   // comments in RegisterSiteInstance.)
   SiteInstanceMap* map = GetSiteInstanceMap(profile_, site_instance->site());
   SiteInstanceMap::iterator i = map->find(site);
   if (i != map->end() && i->second == site_instance) {
     // Matches, so erase it.
     map->erase(i);
   }
 }