Make UseCounter take a LocaFrame instead of any Frame

third_party/WebKit/Source/core/page/FrameTree.cpp

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 33 matching lines @@
 }  // namespace
 
 FrameTree::FrameTree(Frame* this_frame)
     : this_frame_(this_frame), scoped_child_count_(kInvalidChildCount) {}
 
 FrameTree::~FrameTree() {}
 
 const AtomicString& FrameTree::GetName() const {
   // TODO(andypaicu): remove this once we have gathered the data
   if (experimental_set_nulled_name_) {
-    UseCounter::Count(this_frame_.Get(),
-                      UseCounter::kCrossOriginMainFrameNulledNameAccessed);
+    const LocalFrame* frame =
+        this_frame_->IsLocalFrame()
+            ? ToLocalFrame(this_frame_)
+            : (Top().IsLocalFrame() ? ToLocalFrame(&Top()) : nullptr);
+    if (frame) {
+      UseCounter::Count(frame,
+                        UseCounter::kCrossOriginMainFrameNulledNameAccessed);

[dcheng, 2017/05/12 22:15:18]

I think we might want to keep this: can we cheat by using Page::GetUseCounter()
directly?

(I'm actually surprised at how few direct references there are to GetUseCounter)

[Rick Byers, 2017/05/25 15:32:31]

Unfortunately no, in order to migrate UseCounter handling to the browser process
I really need to fix all this "cheating" and associate a real LocalFrame with
each call to Count.  Fundamentally there's always some local frame responsible
for triggering usage, and we might want to treat the usage differently depending
on which frame triggered it.

That said, it's not that big of a deal at the moment to cheat by picking _some_
LocalFrame in the page, but I figured we wouldn't want to search the whole frame
tree to find one.  So in practice I figured it was probably fine to cheat by
picking either the current or top frame here when one was local.  That should
handle most of the cases I think.  

This especially didn't seem worth worrying about too much when the TODO implied
the measurement would likely go away soon.

+    }
   }
   return name_;
 }
 
 // TODO(andypaicu): remove this once we have gathered the data
 void FrameTree::ExperimentalSetNulledName() {
   experimental_set_nulled_name_ = true;
 }
 
 void FrameTree::SetName(const AtomicString& name) {
@@ skipping 230 matching lines @@
 void showFrameTree(const blink::Frame* frame) {
   if (!frame) {
     printf("Null input frame\n");
     return;
   }
 
   printFrames(&frame->Tree().Top(), frame, 0);
 }
 
 #endif