[Sync] Add type conversion constructor for WeakHandle

chrome/browser/sync/notifier/non_blocking_invalidation_notifier_unittest.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 "chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "chrome/browser/sync/notifier/invalidation_version_tracker.h"
@@ skipping 25 matching lines @@
     base::Thread::Options options;
     options.message_loop_type = MessageLoop::TYPE_IO;
     io_thread_.StartIOThread();
     request_context_getter_ = new TestURLRequestContextGetter;
     notifier::NotifierOptions notifier_options;
     notifier_options.request_context_getter = request_context_getter_;
     invalidation_notifier_.reset(
         new NonBlockingInvalidationNotifier(
             notifier_options,
             InvalidationVersionMap(),
-            browser_sync::WeakHandle<InvalidationVersionTracker>(
+            browser_sync::MakeWeakHandle(
                 base::WeakPtr<sync_notifier::InvalidationVersionTracker>()),
             "fake_client_info"));
     invalidation_notifier_->AddObserver(&mock_observer_);
   }
 
   virtual void TearDown() {
     invalidation_notifier_->RemoveObserver(&mock_observer_);
     invalidation_notifier_.reset();
     request_context_getter_ = NULL;
     io_thread_.Stop();
@@ skipping 18 matching lines @@
   invalidation_notifier_->UpdateCredentials("foo@bar.com", "fake_token");
   invalidation_notifier_->UpdateEnabledTypes(types);
 }
 
 // TODO(akalin): Add synchronous operations for testing to
 // NonBlockingInvalidationNotifierTest and use that to test it.
 
 }  // namespace
 
 }  // namespace sync_notifier