renderer: implement multiple permission requesting

content/browser/permissions/permission_pending_single_request.h

+// Copyright 2015 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_PENDING_SINGLE_REQUEST_H_
+#define CONTENT_BROWSER_PERMISSIONS_PERMISSION_PENDING_SINGLE_REQUEST_H_
+
+#include "base/callback_forward.h"
+#include "base/macros.h"
+#include "content/browser/permissions/permission_pending_request.h"
+#include "content/common/permission_service.mojom.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
+#include "url/gurl.h"
+
+namespace content {
+
+enum class PermissionType;
+
+class PermissionPendingSingleRequest : public PermissionPendingRequest {

[mlamouri (slow - plz ping), 2015/08/18 13:37:15]

Could that be simplified to be a special case of multiple permission? In other
words, you drop the class specialization and have only one class for permission
request pendings which will take one or more permission requests. WDYT?

[Lalit Maganti, 2015/08/20 14:23:30]

I'm split about this. It would vastly reduce code complexity but would
unnecessarily introduce overhead by using vectors everywhere rather than plain
objects.

I think it would definitely be good to discuss this further.

+ public:
+  using PermissionStatusCallback = mojo::Callback<void(PermissionStatus)>;
+
+  PermissionPendingSingleRequest(
+      PermissionType permission,
+      const GURL& origin,
+      const PermissionStatusCallback& callback);
+  ~PermissionPendingSingleRequest() override;
+
+  void Cancel(PermissionManager* permission_manager,
+              RenderFrameHost* context,
+              int request_id) override;
+
+  PermissionStatusCallback callback;
+
+ private:
+  PermissionType permission;
+  GURL origin;
+
+ DISALLOW_COPY_AND_ASSIGN(PermissionPendingSingleRequest);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_PERMISSIONS_PERMISSION_PENDING_SINGLE_REQUEST_H_