Trace RenderViewImpl::OnResize

The trace comes handy when unexpected resize message triggers a main
frame.

BUG=392652
TEST=do a trace for scrolling a page on clank during which the top control
     becomes hidden, and found that at the end of scroll there is a
     RenderViewImpl::OnResize trace event.

Review URL: https://codereview.chromium.org/403593003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283947 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/render_view_impl.cc

@@ -3311,6 +3311,7 @@ void RenderViewImpl::OnMoveOrResizeStarted() {
 }
 
 void RenderViewImpl::OnResize(const ViewMsg_Resize_Params& params) {
+  TRACE_EVENT0("renderer", "RenderViewImpl::OnResize");
   if (webview()) {
     webview()->hidePopups();
     if (send_preferred_size_changes_) {