Implement basic mojo Permission service and use it for Geolocation.

content/browser/permissions/permission_service_impl.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.
+
+#ifndef CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_IMPL_H_
+#define CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_IMPL_H_
+
+#include "base/id_map.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/permissions/permission_service_context.h"
+#include "content/common/permission_service.mojom.h"
+#include "content/public/browser/permission_type.h"
+
+namespace content {
+
+// Implements the PermissionService Mojo interface.
+// This service can be created from a RenderFrameHost or a RenderProcessHost.
+// It receives at PermissionContext instance when created (that it then owns)

[blundell, 2014/11/14 14:41:59]

This comment is out of date.

[mlamouri (slow - plz ping), 2014/11/14 16:14:45]

Acknowledged.

+// which allows it to have some information about the current context. That
+// allows the service to know whether it can show UI and have knowledge of the
+// associated WebContents for example.
+class PermissionServiceImpl : public mojo::InterfaceImpl<PermissionService> {
+ public:
+  virtual ~PermissionServiceImpl();
+
+  // Clear pending permissions associated with a given frame and request the
+  // browser to cancel the permission requests.
+  void CancelPendingRequests();
+
+ protected:
+  friend PermissionServiceContext;
+
+  PermissionServiceImpl(PermissionServiceContext* context);
+
+ private:
+  struct PendingRequest {
+    PendingRequest(PermissionType permission, const GURL& origin);
+    PermissionType permission;
+    GURL origin;
+  };
+  typedef IDMap<PendingRequest, IDMapOwnPointer> RequestsMap;
+
+  // PermissionService.
+  void QueryPermission(

[blundell, 2014/11/14 14:42:00]

hmm, QueryPermission and RequestPermission sound confusingly similar.  I liked
HasPermission better, tbh. Or maybe QueryPermissionStatus?

[mlamouri (slow - plz ping), 2014/11/14 16:14:45]

Hmm... HasPermission() has the disadvantage to look like a boolean but meh...
Back to Has.

+      PermissionName permission,
+      const mojo::String& origin,
+      const mojo::Callback<void(PermissionStatus)>& callback) override;
+  void RequestPermission(
+      PermissionName permission,
+      const mojo::String& origin,
+      const mojo::Callback<void(PermissionStatus)>& callback) override;
+
+  // mojo::InterfaceImpl.
+  void OnConnectionError() override;
+
+  void OnRequestPermissionResponse(

[blundell, 2014/11/14 14:42:00]

nit: I think I'd be inclined to call this just OnPermissionResponse.

[mlamouri (slow - plz ping), 2014/11/14 16:14:45]

Hmm, I prefer not to. For two reasons:
- The pattern Foo() -> OnFooResponse() has the advantage of being clear;
- Theere will likely be a callback for getting the current permission status
which might make |OnPermissionResponse| confusing ;)

+    const mojo::Callback<void(PermissionStatus)>& callback,
+    int request_id,
+    bool allowed);
+
+  RequestsMap pending_requests_;
+  PermissionServiceContext* context_;

[blundell, 2014/11/14 14:42:00]

// weak; owns this object.

[mlamouri (slow - plz ping), 2014/11/14 16:14:45]

Done.

+  base::WeakPtrFactory<PermissionServiceImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PermissionServiceImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_PERMISSIONS_PERMISSION_SERVICE_IMPL_H_