Make SkBitmapCache remove invalid bitmaps from the SkResourceCache.

src/core/SkBitmapCache.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkResourceCache.h"
 #include "SkMipMap.h"
@@ skipping 53 matching lines @@
 static bool find_and_return(const BitmapKey& key, SkBitmap* result) {
     const BitmapRec* rec = (BitmapRec*)SkResourceCache::FindAndLock(key);
     if (rec) {
         *result = rec->fBitmap;
         SkResourceCache::Unlock(rec);
 
         result->lockPixels();
         if (result->getPixels()) {
             return true;
         }
-        // todo: we should explicitly purge rec from the cache at this point, since
-        //       it is effectively purged already (has no memory behind it)
+
+        SkResourceCache::Remove(rec);
         result->reset();
         // fall-through to false
     }
     return false;
 }
 
 bool SkBitmapCache::Find(const SkBitmap& src, SkScalar invScaleX, SkScalar invScaleY,
                          SkBitmap* result) {
     if (0 == invScaleX || 0 == invScaleY) {
         // degenerate, and the key we use for mipmaps
@@ skipping 65 matching lines @@
     }
     return result;
 }
 
 void SkMipMapCache::Add(const SkBitmap& src, const SkMipMap* result) {
     if (result) {
         SkResourceCache::Add(SkNEW_ARGS(MipMapRec, (src, result)));
     }
 }