Oilpan: add missing leftmost trace()s for GC mixins.

Source/modules/credentialmanager/CredentialManagerClient.cpp

 // 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 "config.h"
 #include "modules/credentialmanager/CredentialManagerClient.h"
 
 #include "bindings/core/v8/ScriptState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/page/Page.h"
 
 namespace blink {
 
 CredentialManagerClient::CredentialManagerClient(WebCredentialManagerClient* client)
     : m_client(client)
 {
 }
 
 CredentialManagerClient::~CredentialManagerClient()
 {
 }
 
+void CredentialManagerClient::trace(Visitor* visitor)
+{
+    WillBeHeapSupplement<Page>::trace(visitor);
+}
+
 // static
 const char* CredentialManagerClient::supplementName()
 {
     return "CredentialManagerClient";
 }
 
 // static
 CredentialManagerClient* CredentialManagerClient::from(ExecutionContext* executionContext)
 {
     if (!executionContext->isDocument() || !toDocument(executionContext)->page())
@@ skipping 34 matching lines @@
 }
 
 void CredentialManagerClient::dispatchRequest(bool zeroClickOnly, const WebVector<WebURL>& federations, WebCredentialManagerClient::RequestCallbacks* callbacks)
 {
     if (!m_client)
         return;
     m_client->dispatchRequest(zeroClickOnly, federations, callbacks);
 }
 
 } // namespace blink