Remove RefPtrHashMap

The recently added 'HashTraits::PeekInType' type allows us to remove
HashMap<RefPtr..> template specialization without loosing the efficiency
and without bringing any significant changes and complexity to the HashMap
class.

To get rid of 'RefPtrHashMap' a new 'RefPtrValuePeeker' type was created
and used as 'HashTraits::PeekInType' for RefPtr. The 'RefPtrValuePeeker'
class can be constructed either from RefPtr, PassRefPtr or a plain pointer,
then it behaves like a plain pointer itself within HashTable methods.

The proposed change brings the following benefits:
1) Removes tons of duplicated code
2) Allows avoiding ref-count churn also at HashSet<RefPtr>

Review URL: https://codereview.chromium.org/184233006

git-svn-id: svn://svn.chromium.org/blink/trunk@168593 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/wtf/HashMap.h

@@ -526,6 +526,4 @@ namespace WTF {
 
 using WTF::HashMap;
 
-#include "wtf/RefPtrHashMap.h"
-
 #endif /* WTF_HashMap_h */

third_party/WebKit/Source/wtf/HashTraits.h

@@ -170,7 +170,7 @@ namespace WTF {
         static const bool hasIsEmptyValueFunction = true;
         static bool isEmptyValue(const RefPtr<P>& value) { return !value; }
 
-        typedef const RefPtr<P>& PeekInType;
+        typedef RefPtrValuePeeker<P> PeekInType;
         typedef RefPtr<P>* IteratorGetType;
         typedef const RefPtr<P>* IteratorConstGetType;
         typedef RefPtr<P>& IteratorReferenceType;

third_party/WebKit/Source/wtf/RefPtr.h

@@ -188,6 +188,16 @@ namespace WTF {
         return p.get();
     }
 
+    template<typename T> class RefPtrValuePeeker {
+    public:
+        ALWAYS_INLINE RefPtrValuePeeker(T* p): m_ptr(p) { }
+        template<typename U> RefPtrValuePeeker(const RefPtr<U>& p): m_ptr(p.get()) { }
+        template<typename U> RefPtrValuePeeker(const PassRefPtr<U>& p): m_ptr(p.get()) { }
+        ALWAYS_INLINE operator T*() const { return m_ptr; }
+    private:
+        T* m_ptr;
+    };
+
 } // namespace WTF
 
 using WTF::RefPtr;

third_party/WebKit/Source/wtf/wtf.gypi

@@ -99,7 +99,6 @@
             'RefCountedLeakCounter.cpp',
             'RefCountedLeakCounter.h',
             'RefPtr.h',
-            'RefPtrHashMap.h',
             'RetainPtr.h',
             'SHA1.cpp',
             'SHA1.h',