Implement DelegationTracker for tracking delegated permissions to RenderFrameHosts

chrome/browser/permissions/delegation_tracker.h

Index: chrome/browser/permissions/delegation_tracker.h
diff --git a/chrome/browser/permissions/delegation_tracker.h b/chrome/browser/permissions/delegation_tracker.h
new file mode 100644
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+++ b/chrome/browser/permissions/delegation_tracker.h
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+// Copyright 2016 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 CHROME_BROWSER_PERMISSIONS_DELEGATION_TRACKER_H_
+#define CHROME_BROWSER_PERMISSIONS_DELEGATION_TRACKER_H_
+
+#include <memory>
+#include <unordered_map>
+#include <vector>
+
+#include "base/macros.h"
+
+namespace content {
+
+class RenderFrameHost;
+class WebContents;
+enum class PermissionType;
+
+}  // namespace content
+
+// Keeps track of which permissions are delegated to frames. There are two
+// operations possible:
+// 1) Setting the permissions which are delegated to a frame by its parent, and
+// 2) Querying whether a particular permission is granted to a frame.
+//
+// If a frame is destroyed or navigated, permissions will no longer be delegated
+// to it.
+class DelegationTracker {
+ public:
+  DelegationTracker();
+  ~DelegationTracker();
+
+  // Set the |permissions| which are delegated to |child_rfh| by its parent.
+  void SetDelegatedPermissions(
+      content::RenderFrameHost* child_rfh,
+      const std::vector<content::PermissionType>& permissions);
+
+  // Query whether |permission| is granted to |requesting_rfh|. This will return
+  // true if |requesting_rfh| is a top-level frame or if it has been delegated
+  // |permission| through its ancestor frames. Specifically, each frame on the
+  // path between the main frame and |requesting_rfh| must either delegate
+  // |permission| to it's child OR have the same origin as it's child on that
+  // path in order for this to return true.
+  bool IsGranted(content::RenderFrameHost* requesting_rfh,
+                 const content::PermissionType& permission);
+
+ private:
+  class DelegatedForChild;
+
+  void RenderFrameHostChanged(content::RenderFrameHost* rfh);
+
+  std::unordered_map<content::RenderFrameHost*,
+                     std::unique_ptr<DelegatedForChild>>
+      delegated_permissions_;
+
+  DISALLOW_COPY_AND_ASSIGN(DelegationTracker);
+};
+
+#endif  // CHROME_BROWSER_PERMISSIONS_DELEGATION_TRACKER_H_