Don't focus the omnibox when a subframe navigates on NTP.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index db0cf760cfc4157ccbf39a35869061d2f6cf3c87..36be9a3e9204e458c7c57ab270f2b5a330d32e91 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -2173,11 +2173,16 @@ void RenderFrameHostManager::CommitPending() {
                "FrameTreeNode id", frame_tree_node_->frame_tree_node_id());
   DCHECK(pending_render_frame_host_ || speculative_render_frame_host_);
 
+  bool is_main_frame = frame_tree_node_->IsMainFrame();
+
   // First check whether we're going to want to focus the location bar after
   // this commit.  We do this now because the navigation hasn't formally
   // committed yet, so if we've already cleared the pending WebUI the call chain
-  // this triggers won't be able to figure out what's going on.
-  bool will_focus_location_bar = delegate_->FocusLocationBarByDefault();
+  // this triggers won't be able to figure out what's going on.  Note that
+  // subframe commits should not be allowed to steal focus from the main frame
+  // by focusing the location bar (see https://crbug.com/700124).
+  bool will_focus_location_bar =
+      is_main_frame && delegate_->FocusLocationBarByDefault();
 
   // Remember if the page was focused so we can focus the new renderer in
   // that case.
@@ -2185,8 +2190,6 @@ void RenderFrameHostManager::CommitPending() {
                            render_frame_host_->GetView() &&
                            render_frame_host_->GetView()->HasFocus();
 
-  bool is_main_frame = frame_tree_node_->IsMainFrame();
-
   // While the old frame is still current, remove its children from the tree.
   frame_tree_node_->ResetForNewProcess();