Add Mojo API for Blink hit testing

content/browser/frame_host/input/legacy_ipc_frame_input_handler.h

 // Copyright 2017 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_FRAME_HOST_INPUT_LEGACY_IPC_FRAME_INPUT_HANDLER_H_
 #define CONTENT_BROWSER_FRAME_HOST_INPUT_LEGACY_IPC_FRAME_INPUT_HANDLER_H_
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/common/input/input_handler.mojom.h"
 
@@ skipping 29 matching lines @@
   void PasteAndMatchStyle() override;
   void Replace(const base::string16& word) override;
   void ReplaceMisspelling(const base::string16& word) override;
   void Delete() override;
   void SelectAll() override;
   void CollapseSelection() override;
   void SelectRange(const gfx::Point& base, const gfx::Point& extent) override;
   void AdjustSelectionByCharacterOffset(int32_t start, int32_t end) override;
   void MoveRangeSelectionExtent(const gfx::Point& extent) override;
 
+  void HitTestFrameAt(const gfx::PointF& point,
+                      HitTestFrameAtCallback callback) override;
+
  private:
   void SendInput(std::unique_ptr<IPC::Message> message);
 
   RenderFrameHostImpl* frame_host_;
   int routing_id_;
 
   DISALLOW_COPY_AND_ASSIGN(LegacyIPCFrameInputHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_INPUT_LEGACY_IPC_FRAME_INPUT_HANDLER_H_