Implement a persistent uniqueID-based cache for SkImageFilter.

src/core/SkBitmapDevice.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 "SkBitmapDevice.h"
 #include "SkConfig8888.h"
 #include "SkDraw.h"
@@ skipping 349 matching lines @@
             *info = bmInfo;
         }
         if (rowBytes) {
             *rowBytes = fBitmap.rowBytes();
         }
         return fBitmap.getPixels();
     }
     return NULL;
 }
 
+SkImageFilter::UniqueIDCache* SkBitmapDevice::getImageFilterCache() {
+    SkImageFilter::UniqueIDCache* cache = SkImageFilter::UniqueIDCache::Get();
+    cache->ref();
+    return cache;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkBitmapDevice::filterTextFlags(const SkPaint& paint, TextFlags* flags) {
     if (!paint.isLCDRenderText() || !paint.isAntiAlias()) {
         // we're cool with the paint as is
         return false;
     }
 
     if (kN32_SkColorType != fBitmap.colorType() ||
         paint.getRasterizer() ||
         paint.getPathEffect() ||
         paint.isFakeBoldText() ||
         paint.getStyle() != SkPaint::kFill_Style ||
         !SkXfermode::IsMode(paint.getXfermode(), SkXfermode::kSrcOver_Mode)) {
         // turn off lcd
         flags->fFlags = paint.getFlags() & ~SkPaint::kLCDRenderText_Flag;
         flags->fHinting = paint.getHinting();
         return true;
     }
     // we're cool with the paint as is
     return false;
 }