Extensions installed by policy overrun previously installed extensions.

chrome/browser/extensions/pending_extension_manager.cc

 // Copyright (c) 2011 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 "base/logging.h"
 #include "base/stl_util.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/pending_extension_manager.h"
 #include "chrome/common/extensions/extension.h"
 #include "content/browser/browser_thread.h"
@@ skipping 50 matching lines @@
 
   const bool kIsFromSync = true;
   const Extension::Location kSyncLocation = Extension::INTERNAL;
 
   return AddExtensionImpl(id, update_url, should_allow_install,
                           kIsFromSync, install_silently, kSyncLocation);
 }
 
 void PendingExtensionManager::AddFromExternalUpdateUrl(
     const std::string& id, const GURL& update_url,
-    Extension::Location location) {
+    Extension::Location location, bool overwrite) {

[Sam Kerner (Chrome), 2011/08/10 17:21:09]

There are two reasons |overwrite| is useful:

1) The new location has a higher priority than the old one.

2) The extension is already installed, and you want to avoid the LOG(DFATAL).

I would prefer that PendingExtensionManager methods enforce the invariant that
the higher-ranked location wins.  Instead of adding the overwrite parameter,
lets solve #1 by using Extension::GetHigherPriorityLocation() to see if an
existing record should be overwritten.  #2 can be solved by LOG(DFATAL)ing only
when the new location does not outrank the old location.

[Joao da Silva, 2011/08/11 10:03:23]

Done.

   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   const bool kIsFromSync = false;
   const bool kInstallSilently = true;
 
-  if (service_.IsExternalExtensionUninstalled(id))
-    return;
+  if (!overwrite) {
+    if (service_.IsExternalExtensionUninstalled(id)) {
+      return;
+    }
 
-  if (service_.GetInstalledExtension(id)) {
-    LOG(DFATAL) << "Trying to add extension " << id
-                << " by external update, but it is already installed.";
-    return;
+    if (service_.GetInstalledExtension(id)) {
+      LOG(DFATAL) << "Trying to add extension " << id
+                  << " by external update, but it is already installed.";
+      return;
+    }
   }
 
   AddExtensionImpl(id, update_url, &AlwaysInstall,
                    kIsFromSync, kInstallSilently,
                    location);
 }
 
 
 void PendingExtensionManager::AddFromExternalFile(
     const std::string& id,
@@ skipping 55 matching lines @@
     return true;
   }
   return false;
 }
 
 void PendingExtensionManager::AddForTesting(
     const std::string& id,
     const PendingExtensionInfo& pending_extension_info) {
   pending_extension_map_[id] = pending_extension_info;
 }