Use FrameTreeNode ID as frameId in extension APIs

content/browser/web_contents/web_contents_impl.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/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 746 matching lines @@
   return frame_tree_.root()->current_frame_host();
 }
 
 RenderFrameHostImpl* WebContentsImpl::GetFocusedFrame() {
   FrameTreeNode* focused_node = frame_tree_.GetFocusedFrame();
   if (!focused_node)
     return nullptr;
   return focused_node->current_frame_host();
 }
 
+RenderFrameHostImpl* WebContentsImpl::FindByFrameTreeNodeID(
+    int frame_tree_node_id) {
+  FrameTreeNode* frame = frame_tree_.FindByID(frame_tree_node_id);
+  return frame ? frame->current_frame_host() : nullptr;
+}
+
 void WebContentsImpl::ForEachFrame(
     const base::Callback<void(RenderFrameHost*)>& on_frame) {
   frame_tree_.ForEach(base::Bind(&ForEachFrameInternal, on_frame));
 }
 
 void WebContentsImpl::SendToAllFrames(IPC::Message* message) {
   ForEachFrame(base::Bind(&SendToAllFramesInternal, message));
   delete message;
 }
 
@@ skipping 3863 matching lines @@
   return NULL;
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content