Pick frame to navigate in the browser process.

content/browser/frame_host/frame_tree.h

Index: content/browser/frame_host/frame_tree.h
diff --git a/content/browser/frame_host/frame_tree.h b/content/browser/frame_host/frame_tree.h
index ce34bc287f1ea9ad6206d832666dd762b078f9fd..f0a8bbc618eb30048ef28dfd888ba21eb7cff7c5 100644
--- a/content/browser/frame_host/frame_tree.h
+++ b/content/browser/frame_host/frame_tree.h
@@ -59,6 +59,12 @@ class CONTENT_EXPORT FrameTree {
   // Returns the FrameTreeNode with the given renderer-specific |routing_id|.
   FrameTreeNode* FindByRoutingID(int process_id, int routing_id);
 
+  // Returns the first frame in this tree with the given |name|, or the main
+  // frame if |name| is empty.
+  // Note that this does NOT support pseudo-names like _self, _top, and _blank,
+  // nor searching other FrameTrees (unlike blink::WebView::findFrameByName).
+  FrameTreeNode* FindByName(const std::string& name);
+
   // Executes |on_node| on each node in the frame tree.  If |on_node| returns
   // false, terminates the iteration immediately. Returning false is useful
   // if |on_node| is just doing a search over the tree.  The iteration proceeds