Add trace event for detecting main frame in loading metrics.

third_party/WebKit/Source/web/WebFrame.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "public/web/WebFrame.h"
 
 #include "bindings/core/v8/WindowProxyManager.h"
 #include "core/HTMLNames.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/RemoteFrame.h"
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/page/Page.h"
 #include "platform/UserGestureIndicator.h"
 #include "platform/heap/Handle.h"
+#include "platform/instrumentation/tracing/TraceEvent.h"
 #include "public/web/WebElement.h"
 #include "public/web/WebFrameOwnerProperties.h"
 #include "public/web/WebSandboxFlags.h"
 #include "web/OpenedFrameTracker.h"
 #include "web/RemoteFrameOwner.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebRemoteFrameImpl.h"
 #include <algorithm>
 
 namespace blink {
@@ skipping 64 matching lines @@
     // In this case, the core LocalFrame is already initialized, so just
     // update a bit of state.
     LocalFrame& localFrame = *toWebLocalFrameImpl(frame)->frame();
     DCHECK_EQ(owner, localFrame.owner());
     if (owner) {
       owner->setContentFrame(localFrame);
       if (owner->isLocal())
         toHTMLFrameOwnerElement(owner)->setWidget(localFrame.view());
     } else {
       localFrame.page()->setMainFrame(&localFrame);
+      // This trace event is needed to detect the main frame of the
+      // renderer in telemetry metrics. See crbug.com/692112#c11.
+      TRACE_EVENT_INSTANT1("loading", "markAsMainFrame",
+                           TRACE_EVENT_SCOPE_THREAD, "frame", &localFrame);
     }
   } else {
     toWebRemoteFrameImpl(frame)->initializeCoreFrame(host, owner, name,
                                                      uniqueName);
   }
 
   if (oldFrame->hasReceivedUserGesture())
     frame->toImplBase()->frame()->setDocumentHasReceivedUserGesture();
 
   frame->toImplBase()->frame()->getWindowProxyManager()->setGlobals(globals);
@@ skipping 196 matching lines @@
   for (WebFrame* child = frame->firstChild(); child;
        child = child->nextSibling())
     traceFrame(visitor, child);
 }
 
 void WebFrame::close() {
   m_openedFrameTracker->dispose();
 }
 
 }  // namespace blink