Implement basic mojo Permission service and use it for Geolocation.

content/browser/permissions/permission_service_context.h

+// 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 "base/macros.h"
+#include "content/public/browser/web_contents_observer.h"
+
+#ifndef CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_CONTEXT_H_
+#define CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_CONTEXT_H_
+
+namespace content {
+
+class PermissionServiceImpl;
+class RenderFrameHost;
+
+// Provides information to a PermissionService. It is used by the
+// PermissionService to handle request permission UI.

[nasko, 2014/11/13 23:57:37]

Since this class has a member pointer to RenderFrameHost, it will be useful to
put in the description what is the relationship and lifetime of this object. Is
it one per RFH? Who creates/destroys it?

[mlamouri (slow - plz ping), 2014/11/14 00:16:33]

There is one per RFH. Created when the RFH is created, then owned by the
PermissionService. I will add a comment explaining that.

+class PermissionServiceContext : public WebContentsObserver {
+ public:
+  explicit PermissionServiceContext(RenderFrameHost* render_frame_host);
+  virtual ~PermissionServiceContext();
+
+  // WebContentsObserver
+  void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
+  void DidNavigateAnyFrame(RenderFrameHost* render_frame_host,
+                           const LoadCommittedDetails& details,
+                           const FrameNavigateParams& params) override;
+
+  RenderFrameHost* render_frame_host();
+
+  void set_service(PermissionServiceImpl* service);
+
+ private:
+  RenderFrameHost* render_frame_host_;
+  PermissionServiceImpl* service_;
+
+  DISALLOW_COPY_AND_ASSIGN(PermissionServiceContext);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_CONTEXT_H_