Fix force policy installation of the removed pref-installed extension

chrome/browser/extensions/pending_extension_manager.cc

 // Copyright 2014 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/extensions/pending_extension_manager.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 176 matching lines @@
   static const bool kIsFromSync = false;
   static const bool kRemoteInstall = false;
 
   const Extension* extension = ExtensionRegistry::Get(context_)
       ->GetExtensionById(id, ExtensionRegistry::EVERYTHING);
   if (extension && location == Manifest::GetHigherPriorityLocation(
                                    location, extension->location())) {
     // If the new location has higher priority than the location of an existing
     // extension, let the update process overwrite the existing extension.
   } else {
-    if (ExtensionPrefs::Get(context_)->IsExternalExtensionUninstalled(id))
+    // Skip the installation if the extension was removed by the user and it's
+    // not specified to be force-installed through the policy.
+    if (!Manifest::IsPolicyLocation(location) &&
+        ExtensionPrefs::Get(context_)->IsExternalExtensionUninstalled(id)) {
       return false;
+    }
 
     if (extension) {
       LOG(DFATAL) << "Trying to add extension " << id
                   << " by external update, but it is already installed.";
       return false;
     }
   }
 
   return AddExtensionImpl(id,
                           install_parameter,
@@ skipping 113 matching lines @@
 
   return true;
 }
 
 void PendingExtensionManager::AddForTesting(
     const PendingExtensionInfo& pending_extension_info) {
   pending_extension_list_.push_back(pending_extension_info);
 }
 
 }  // namespace extensions