Refactor IntersectionGeometry class and move it to core/layout.

third_party/WebKit/Source/core/dom/IntersectionObservation.h

 // Copyright 2016 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.
 
 #ifndef IntersectionObservation_h
 #define IntersectionObservation_h
 
 #include "core/dom/DOMHighResTimeStamp.h"
-#include "core/dom/IntersectionGeometry.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class Element;
 class IntersectionObserver;
 
 class IntersectionObservation final
     : public GarbageCollected<IntersectionObservation> {
  public:
-  IntersectionObservation(
-      IntersectionObserver&,
-      Element&,
-      IntersectionGeometry::ReportRootBounds shouldReportRootBounds);
+  IntersectionObservation(IntersectionObserver&,
+                          Element&,
+                          bool shouldReportRootBounds);

[xjz, 2016/12/07 01:01:14]

ooc, I did this bool to enum change as suggested by ojan@. Any reason to revert
it? 

[szager1, 2016/12/07 01:30:49]

I should talk to Ojan about that.  My reasons:

- Fewer files need to #include "core/layout/IntersectionGeometry."
- Using an enum for bool values is, IMO, the worst kind of syntactic sugar.

Maybe Ojan was thinking that we would want to support other values in the
future?  I can't think of what they might be.

[xjz, 2016/12/07 01:53:56]

I agree with you that using bool makes codes simpler.
FYI, the following is what he commented on my CL:
"Also, we generally try to avoid boolean arguments to functions unless it's
obvious what the bool is because it makes it hard to know what they are. From
the C++ style guide "Consider changing the function signature to replace a bool
argument with an enum argument. This will make the argument values
self-describing."

The typical solution here is to create an enum:
enum class IntersectionGeometryBounds {
  kShouldReportRootBounds,
  kShouldNotReportRootBounds,
}"

[szager1, 2016/12/07 02:03:49]

I would argue that "it's obvious what the bool is."  Using values like
kShouldReportRootBounds for a variable named shouldReportRootBounds is pretty
redundant.

 
   IntersectionObserver& observer() const { return *m_observer; }
   Element* target() const { return m_target; }
   unsigned lastThresholdIndex() const { return m_lastThresholdIndex; }
   void setLastThresholdIndex(unsigned index) { m_lastThresholdIndex = index; }
   void computeIntersectionObservations(DOMHighResTimeStamp);
   void disconnect();
   void clearRootAndRemoveFromTarget();
 
   DECLARE_TRACE();
 
  private:
   Member<IntersectionObserver> m_observer;
   WeakMember<Element> m_target;
 
   const unsigned m_shouldReportRootBounds : 1;
   unsigned m_lastThresholdIndex : 30;
 };
 
 }  // namespace blink
 
 #endif  // IntersectionObservation_h