Special-case LocalDOMWindow for same-origin access in bindings.

third_party/WebKit/Source/core/timing/Performance.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 168 matching lines @@
 }
 
 /**
  * Report sanitized name based on cross-origin policy.
  * See detailed Security doc here: http://bit.ly/2duD3F7
  */
 // static
 std::pair<String, DOMWindow*> Performance::sanitizedAttribution(
     ExecutionContext* taskContext,
     bool hasMultipleContexts,
-    Frame* observerFrame) {
+    LocalFrame* observerFrame) {
   if (hasMultipleContexts) {
     // Unable to attribute, multiple script execution contents were involved.
     return std::make_pair(kAmbiguousAttribution, nullptr);
   }
 
   if (!taskContext || !taskContext->isDocument() ||
       !toDocument(taskContext)->frame()) {
     // Unable to attribute as no script was involved.
     return std::make_pair(kUnknownAttribution, nullptr);
   }
@@ skipping 30 matching lines @@
   return std::make_pair(kCrossOriginAttribution, nullptr);
 }
 
 void Performance::reportLongTask(double startTime,
                                  double endTime,
                                  ExecutionContext* taskContext,
                                  bool hasMultipleContexts) {
   std::pair<String, DOMWindow*> attribution = Performance::sanitizedAttribution(
       taskContext, hasMultipleContexts, frame());
   DOMWindow* culpritDomWindow = attribution.second;
-  if (!culpritDomWindow || !culpritDomWindow->document() ||
-      !culpritDomWindow->document()->localOwner()) {
-    addLongTaskTiming(startTime, endTime, attribution.first, "", "", "");
+  if (!culpritDomWindow || !culpritDomWindow->frame() ||
+      !culpritDomWindow->frame()->deprecatedLocalOwner()) {
+    addLongTaskTiming(startTime, endTime, attribution.first, emptyString(),
+                      emptyString(), emptyString());

[dcheng, 2017/02/01 07:22:59]

To avoid constructing three new empty strings.

   } else {
     HTMLFrameOwnerElement* frameOwner =
-        culpritDomWindow->document()->localOwner();
+        culpritDomWindow->frame()->deprecatedLocalOwner();
     addLongTaskTiming(startTime, endTime, attribution.first,
                       getFrameAttribute(frameOwner, HTMLNames::srcAttr, false),
                       getFrameAttribute(frameOwner, HTMLNames::idAttr, false),
                       getFrameAttribute(frameOwner, HTMLNames::nameAttr, true));
   }
 }
 
 }  // namespace blink