Use FrameTreeNode ID as frameId in extension APIs

extensions/browser/extension_api_frame_id_map.h

Index: extensions/browser/extension_api_frame_id_map.h
diff --git a/extensions/browser/extension_api_frame_id_map.h b/extensions/browser/extension_api_frame_id_map.h
new file mode 100644
index 0000000000000000000000000000000000000000..176099b48195223adc944dbeb99b1fc8ae25cd9a
--- /dev/null
+++ b/extensions/browser/extension_api_frame_id_map.h
@@ -0,0 +1,134 @@
+// 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 EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_
+#define EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_
+
+#include <list>
+#include <map>
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/lazy_instance.h"
+#include "base/synchronization/lock.h"
+
+namespace content {
+class RenderFrameHost;
+class WebContents;
+}  // namespace content
+
+namespace extensions {
+
+// Extension frame IDs are exposed through the chrome.* APIs and have the
+// following characteristics:
+// - The top-level frame has ID 0.
+// - Any child frame has a positive ID.
+// - A non-existant frame has ID -1.
+// - They are only guaranteed to be unique within a tab.
+// - The ID does not change during the frame's lifetime and is not re-used after
+//   the frame is removed. The frame may change its current RenderFrameHost over
+//   time, so multiple RenderFrameHosts may map to the same extension frame ID.
+struct ExtensionApiFrameId {
+  static const int kInvalidFrameId = -1;
+
+  ExtensionApiFrameId();
+  ExtensionApiFrameId(int frame_id, int parent_frame_id);
+
+  bool operator==(const ExtensionApiFrameId& other) const {
+    return frame_id == other.frame_id &&
+           parent_frame_id == other.parent_frame_id;
+  }
+
+  // The name "ExtensionApiFrameId" refers to |frame_id|.
+  int frame_id;
+
+  // The extension frame ID of the parent frame ID is also included because
+  // some extension APIs need both IDs.
+  int parent_frame_id;
+};
+
+// This class provides a mapping from a (render_process_id, frame_routing_id)
+// pair that maps a RenderFrameHost to an extension frame ID.
+// Unless stated otherwise, the methods can only be called on the UI thread.
+class ExtensionApiFrameIdMap {
+ public:
+  using FrameIdCallback = base::Callback<void(const ExtensionApiFrameId&)>;
+
+  static ExtensionApiFrameIdMap* Get();
+
+  // Runs |callback| with the result that is equivalent to calling GetFrameId()
+  // on the UI thread. If the result was cached the callback is immediately run.
+  // Otherwise the callback is queued and run in order when the result becomes
+  // available. Queued callbacks are not called when the class is destroyed.
+  void GetFrameIdOnIO(int render_process_id,
+                      int frame_routing_id,
+                      const FrameIdCallback& callback);
+
+  // Get the frameId for a RenderFrameHost identified by |render_process_id| and
+  // |frame_routing_id|. These methods always returns the same value when called
+  // with the same parameters.
+  const ExtensionApiFrameId& GetFrameId(int render_process_id,
+                                        int frame_routing_id);
+  const ExtensionApiFrameId& GetFrameId(content::RenderFrameHost* rfh);
+
+  // Find the current RenderFrameHost for a given WebContents and extension
+  // frame ID.
+  // Returns nullptr if not found.
+  content::RenderFrameHost* GetRenderFrameHostById(
+      content::WebContents* web_contents,
+      int frame_id);
+
+ protected:
+  friend struct base::DefaultLazyInstanceTraits<ExtensionApiFrameIdMap>;
+  FRIEND_TEST_ALL_PREFIXES(ExtensionApiFrameIdMapTest, Basic);
+  FRIEND_TEST_ALL_PREFIXES(ExtensionApiFrameIdMapTest, GetFrameIdOnIO);
+
+  // A set of identifiers that uniquely identifies a RenderFrame.
+  struct RenderFrameIdKey {
+    RenderFrameIdKey();
+    RenderFrameIdKey(int render_process_id, int frame_routing_id);
+
+    // The process ID of the renderer that contains the RenderFrame.
+    int render_process_id;
+    // The routing ID of the RenderFrame.
+    int frame_routing_id;
+
+    bool operator<(const RenderFrameIdKey& other) const;
+  };
+
+  // This is a std::list so that iterators are not invalidated when the list is
+  // modified during an iteration.
+  using FrameIdCallbackList = std::list<FrameIdCallback>;
+  using FrameIdMap = std::map<RenderFrameIdKey, ExtensionApiFrameId>;
+  using CallbackMap = std::map<RenderFrameIdKey, FrameIdCallbackList>;
+
+  ExtensionApiFrameIdMap();
+  ~ExtensionApiFrameIdMap();
+
+  // Determines the value to be stored in |frame_id_map_| for a given key.
+  // virtual for testing.
+  virtual ExtensionApiFrameId KeyToValue(const RenderFrameIdKey& key) const;
+
+  const ExtensionApiFrameId& LookupFrameIdOnUI(const RenderFrameIdKey& key);
+  void GotFrameIdOnIO(const RenderFrameIdKey& key);
+
+  // Queued callbacks for use on the IO thread. This queue is only used when the
+  // frameId needs to be fetched from the UI thread.
+  CallbackMap callbacks_map_;
+
+  // This frameId map is only modified on the UI thread and used for 2 purposes:
+  // - On the IO thread, it avoids unnecessary thread hops.
+  // - On the UI thread and the IO thread, it ensures that the frameId remains
+  //   constant, even after removing a frame.
+  // Items are never removed from this map.
+  FrameIdMap frame_id_map_;
+
+  // This lock protects |frame_id_map| from being concurrently written on the UI
+  // thread and read on the IO thread.
+  base::Lock frame_id_map_lock_;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_