media: Implement MediaDrmStorageImpl with tests

components/cdm/browser/media_drm_storage_impl.h

 // Copyright 2017 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.
 
 #ifndef COMPONENTS_CDM_BROWSER_MEDIA_DRM_STORAGE_IMPL_H_
 #define COMPONENTS_CDM_BROWSER_MEDIA_DRM_STORAGE_IMPL_H_
 
+#include "base/threading/thread_checker.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "media/mojo/interfaces/media_drm_storage.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "url/origin.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace content {
@@ skipping 28 matching lines @@
       const LoadPersistentSessionCallback& callback) final;
   void RemovePersistentSession(
       const std::string& session_id,
       const RemovePersistentSessionCallback& callback) final;
 
   // content::WebContentsObserver implementation.
   void RenderFrameDeleted(content::RenderFrameHost* render_frame_host) final;
   void DidFinishNavigation(content::NavigationHandle* navigation_handle) final;
 
  private:
+  base::ThreadChecker thread_checker_;
+
   // Stops observing WebContents and delete |this|.
   void Close();
 
   content::RenderFrameHost* const render_frame_host_ = nullptr;
   PrefService* const pref_service_ = nullptr;
   const url::Origin origin_;
+  const std::string origin_string_;
   bool initialized_ = false;
 
   mojo::Binding<media::mojom::MediaDrmStorage> binding_;
 };
 
 }  // namespace cdm
 
 #endif  // COMPONENTS_CDM_BROWSER_MEDIA_DRM_STORAGE_IMPL_H_