Implement ManifestManager to handle manifest in content/

content/browser/manifest/manifest_manager_host.h

Index: content/browser/manifest/manifest_manager_host.h
diff --git a/content/browser/manifest/manifest_manager_host.h b/content/browser/manifest/manifest_manager_host.h
new file mode 100644
index 0000000000000000000000000000000000000000..f511991344b1ee4e4424b10b49445404f13589c3
--- /dev/null
+++ b/content/browser/manifest/manifest_manager_host.h
@@ -0,0 +1,48 @@
+// 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.
+
+#ifndef CONTENT_RENDERER_MANIFEST_MANIFEST_MANAGER_HOST_H_
+#define CONTENT_RENDERER_MANIFEST_MANIFEST_MANAGER_HOST_H_
+
+#include "base/callback_forward.h"
+#include "base/id_map.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+
+class RenderFrameHost;
+class WebContents;
+struct Manifest;
+
+// ManifestManagerHost is a helper class that allows callers to get the Manifest
+// associated with a frame. It handles the IPC messaging with the child process.
+// TODO(mlamouri): keep a cached version and a dirty bit here.
+class ManifestManagerHost : public WebContentsObserver {
+ public:
+  explicit ManifestManagerHost(WebContents* web_contents);
+  virtual ~ManifestManagerHost();
+
+  typedef base::Callback<void(const Manifest&)> GetManifestCallback;
+
+  // Calls the given callback with the manifest associated with the
+  // given RenderFrameHost. If the frame has no manifest or if getting it failed
+  // the callback will have an empty manifest.
+  void GetManifest(RenderFrameHost*, const GetManifestCallback&);
+
+  // WebContentsObserver
+  virtual bool OnMessageReceived(const IPC::Message&,
+                                 RenderFrameHost*) OVERRIDE;
+
+ private:
+  void OnRequestManifestResponse(int request_id, const Manifest& manifest);
+
+  typedef IDMap<GetManifestCallback, IDMapOwnPointer> CallbackMap;
+  CallbackMap pending_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestManagerHost);
+};
+
+} // namespace content
+
+#endif // CONTENT_RENDERER_MANIFEST_MANIFEST_MANAGER_HOST_H_