Disable install of new default_apps for existing users

chrome/browser/extensions/external_provider_impl.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/extensions/external_provider_impl.h"
 
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/memory/linked_ptr.h"
@@ skipping 207 matching lines @@
         path = base_path.Append(external_crx);
       }
 
       Version version(external_version);
       if (!version.IsValid()) {
         LOG(WARNING) << "Malformed extension dictionary for extension: "
                      << extension_id.c_str() << ".  Invalid version string \""
                      << external_version << "\".";
         continue;
       }
-      service_->OnExternalExtensionFileFound(extension_id, &version, path,
-                                             crx_location_, creation_flags,
-                                             auto_acknowledge_);
+      // Don't install new default apps for existing users.
+      // TODO(grv): remove after migration (Q1-2013).
+      if ((!default_apps::isMigration) || IsOldDefaultApp(extension_id)) {

[Mihai Parparita -not on Chrome, 2012/08/27 19:31:55]

Reading global variables like this is a pretty big hack. It also spreads
knowledge of default apps across more files, instead of being localized in
default_apps.cc.

How about an alterate design where there ExternalProviderImpl subclass in
default_apps.h|cc overrides SetPrefs, and if a migration is happening, filters
out the preference keys before invoking the default SetPrefs implementation?

+        service_->OnExternalExtensionFileFound(extension_id, &version, path,
+                                               crx_location_, creation_flags,
+                                               auto_acknowledge_);
+      } else {
+        continue;
+      }
     } else { // if (has_external_update_url)
       CHECK(has_external_update_url);  // Checking of keys above ensures this.
       if (download_location_ == Extension::INVALID) {
         LOG(WARNING) << "This provider does not support installing external "
                      << "extensions from update URLs.";
         continue;
       }
       GURL update_url(external_update_url);
       if (!update_url.is_valid()) {
         LOG(WARNING) << "Malformed extension dictionary for extension: "
@@ skipping 10 matching lines @@
   for (std::set<std::string>::iterator it = unsupported_extensions.begin();
        it != unsupported_extensions.end(); ++it) {
     // Remove extension for the list of know external extensions. The extension
     // will be uninstalled later because provider doesn't provide it anymore.
     prefs_->Remove(*it, NULL);
   }
 
   service_->OnExternalProviderReady(this);
 }
 
+bool ExternalProviderImpl::IsOldDefaultApp(const std::string& extension_id) {
+  const std::string gmail_id = "pjkljhegncpnkpknbcohdijeoejaedia";
+  const std::string search_id = "coobgpohoikkiipiblmjeljniedjpjpf";
+  const std::string youtube_id = "blpcfgokakmgnkcojhhkbfbldkacnbeo";
+  return extension_id == gmail_id || extension_id == search_id
+      || extension_id == youtube_id;
+}
+
 void ExternalProviderImpl::ServiceShutdown() {
   service_ = NULL;
 }
 
 bool ExternalProviderImpl::IsReady() const {
   return ready_;
 }
 
 bool ExternalProviderImpl::HasExtension(
     const std::string& id) const {
@@ skipping 147 matching lines @@
               service,
               connector->GetAppPackUpdater()->CreateExternalLoader(),
               Extension::EXTERNAL_PREF,
               Extension::INVALID,
               Extension::NO_FLAGS)));
   }
 #endif
 }
 
 }  // namespace extensions