revise SkTDynamicHash and add unit tests

src/core/SkScaledImageCache.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkScaledImageCache.h"
 #include "SkMipMap.h"
 #include "SkPixelRef.h"
@@ skipping 232 matching lines @@
     Key key;
     if (!key.init(orig, scaleX, scaleY)) {
         return NULL;
     }
 
     Rec* rec = SkNEW_ARGS(Rec, (key, scaled));
     this->addToHead(rec);
     SkASSERT(1 == rec->fLockCount);
 
 #ifdef USE_HASH
-    fHash->add(key, rec);
+    fHash->add(rec);
 #endif
 
     // We may (now) be overbudget, so see if we need to purge something.
     this->purgeAsNeeded();
     return (ID*)rec;
 }
 
 SkScaledImageCache::ID* SkScaledImageCache::addAndLockMip(const SkBitmap& orig,
                                                           const SkMipMap* mip) {
     Key key;
     if (!key.init(orig, 0, 0)) {
         return NULL;
     }
 
     Rec* rec = SkNEW_ARGS(Rec, (key, mip));
     this->addToHead(rec);
     SkASSERT(1 == rec->fLockCount);
 
 #ifdef USE_HASH
-    fHash->add(key, rec);
+    fHash->add(rec);
 #endif
 
     // We may (now) be overbudget, so see if we need to purge something.
     this->purgeAsNeeded();
     return (ID*)rec;
 }
 
 void SkScaledImageCache::unlock(SkScaledImageCache::ID* id) {
     SkASSERT(id);
 
@@ skipping 232 matching lines @@
     return SkScaledImageCache::GetBytesUsed();
 }
 
 size_t SkGraphics::GetImageCacheByteLimit() {
     return SkScaledImageCache::GetByteLimit();
 }
 
 size_t SkGraphics::SetImageCacheByteLimit(size_t newLimit) {
     return SkScaledImageCache::SetByteLimit(newLimit);
 }