Add trace event to debug jank issue

BUG=905461

Change-Id: Idee52c3f44ca7aef6707e010b5e07bd668120109
Reviewed-on: https://chromium-review.googlesource.com/c/1330735Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: ssid <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608179}

content/browser/android/web_contents_observer_proxy.cc

@@ -11,6 +11,7 @@
 #include "base/android/scoped_java_ref.h"
 #include "base/optional.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/trace_event/trace_event.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/android/media_metadata_android.h"
@@ -162,6 +163,8 @@ void WebContentsObserverProxy::DidFinishNavigation(
   ScopedJavaLocalRef<jstring> jerror_description =
       ConvertUTF8ToJavaString(env, "");
 
+  // Remove after fixing https://crbug/905461.
+  TRACE_EVENT0("browser", "Java_WebContentsObserverProxy_didFinishNavigation");
   Java_WebContentsObserverProxy_didFinishNavigation(
       env, java_observer_, jstring_url, navigation_handle->IsInMainFrame(),
       navigation_handle->IsErrorPage(), navigation_handle->HasCommitted(),