Add a new top-level inspector timeline event for the PrePaint step

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 20aa9f46aa577f6803618959df897b0057191936..3acee2fd2dd63684967695988ba8b6d1264dd95c 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -2986,6 +2986,8 @@ void FrameView::performScrollAnchoringAdjustments() {
 void FrameView::prePaint() {
   TRACE_EVENT0("blink", "FrameView::prePaint");
   SCOPED_BLINK_UMA_HISTOGRAM_TIMER("Blink.PrePaint.UpdateTime");
+  TRACE_EVENT1("devtools.timeline", "PreparePaint", "data",
+               InspectorPreparePaintEvent::data(m_frame.get()));
 
   if (!m_paintController)
     m_paintController = PaintController::create();