Use FrameTreeNode ID as frameId in extension APIs

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index 39e9fc5c4d805792d3c1c0e2739b5b8ac5143f44..cca3eb68046b0dbba2be7eb60829bb7d8566e9f6 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -134,6 +134,11 @@ RenderFrameHost* RenderFrameHost::FromID(int render_process_id,
 }
 
 // static
+RenderFrameHost* RenderFrameHost::FromFrameTreeNodeID(int frame_tree_node_id) {
+  return RenderFrameHostImpl::FromFrameTreeNodeID(frame_tree_node_id);
+}
+
+// static
 void RenderFrameHost::AllowInjectingJavaScriptForAndroidWebView() {
   g_allow_injecting_javascript = true;
 }
@@ -149,6 +154,15 @@ RenderFrameHostImpl* RenderFrameHostImpl::FromID(int process_id,
 }
 
 // static
+RenderFrameHostImpl* RenderFrameHostImpl::FromFrameTreeNodeID(
+    int frame_tree_node_id) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  FrameTreeNode* frame_tree_node =
+      FrameTreeNode::GloballyFindByID(frame_tree_node_id);
+  return frame_tree_node ? frame_tree_node->current_frame_host() : nullptr;
+}
+
+// static
 RenderFrameHost* RenderFrameHost::FromAXTreeID(
     int ax_tree_id) {
   return RenderFrameHostImpl::FromAXTreeID(ax_tree_id);
@@ -273,6 +287,17 @@ RenderFrameHost* RenderFrameHostImpl::GetParent() {
   return parent_node->current_frame_host();
 }
 
+RenderFrameHost* RenderFrameHostImpl::FindByFrameTreeNodeID(
+    int frame_tree_node_id) {
+  FrameTreeNode* child =
+      frame_tree_node_->frame_tree()->FindByID(frame_tree_node_id);

[Charlie Reis, 2015/10/30 23:25:09]

This doesn't quite match the documentation, which says that it only returns this
node or one of its children.  This code could return a parent if called on a
subframe.

If you're just looking to return a frame from the current frame tree, I might
suggest putting the method on WebContents instead?

[robwu, 2015/10/31 00:10:45]

I was reading frame_tree() as the frame tree rooted at the given node. If that's
incorrect, what do you suggest if I really want to look at the node and its
descendants only?

[robwu, 2015/11/02 19:08:34]

Done.

[Charlie Reis, 2015/11/03 00:23:49]

No, a FrameTree represents the whole tree, starting from the root (main frame).
Hopefully this isn't needed anymore, but you could recursively traverse the
children of the FrameTreeNode if you needed it.

+  return child ? child->current_frame_host() : nullptr;
+}
+
+int RenderFrameHostImpl::GetFrameTreeNodeID() {
+  return frame_tree_node_->frame_tree_node_id();
+}
+
 const std::string& RenderFrameHostImpl::GetFrameName() {
   return frame_tree_node_->frame_name();
 }