Add Mojo API for Blink hit testing

content/renderer/render_widget.cc

 // Copyright (c) 2012 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.
 
 #include "content/renderer/render_widget.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 826 matching lines @@
   if (dispatch_type == DISPATCH_TYPE_BLOCKING) {
     callback = base::Bind(
         &RenderWidget::SendInputEventAck, this, input_event->GetType(),
         ui::WebInputEventTraits::GetUniqueTouchEventId(*input_event));
   }
   input_handler_->HandleInputEvent(
       blink::WebCoalescedInputEvent(*input_event, coalesced_events),
       latency_info, std::move(callback));
 }
 
+int RenderWidget::HitTestFrameAt(const gfx::Point& point) {
+  return input_handler_->HitTestFrameAt(point);
+}
+
 void RenderWidget::HandleInputEvent(
     const blink::WebCoalescedInputEvent& input_event,
     const ui::LatencyInfo& latency_info,
     HandledEventCallback callback) {
   input_handler_->HandleInputEvent(input_event, latency_info,
                                    std::move(callback));
 }
 
 void RenderWidget::SendInputEventAck(
     blink::WebInputEvent::Type type,
@@ skipping 1547 matching lines @@
     // browser side (https://crbug.com/669219).
     // If there is no WebFrameWidget, then there will be no
     // InputMethodControllers for a WebLocalFrame.
     return nullptr;
   }
   return static_cast<blink::WebFrameWidget*>(GetWebWidget())
       ->GetActiveWebInputMethodController();
 }
 
 }  // namespace content