Make SkBitmapCache remove invalid bitmaps from the SkResourceCache.

src/core/SkBitmapCache.cpp

Index: src/core/SkBitmapCache.cpp
diff --git a/src/core/SkBitmapCache.cpp b/src/core/SkBitmapCache.cpp
index c954a3099e67d44232c1969a7e9814325b287e9b..6d4f4b4cc7d7349173f34048e9ba36a16cd1c508 100644
--- a/src/core/SkBitmapCache.cpp
+++ b/src/core/SkBitmapCache.cpp
@@ -71,8 +71,8 @@ static bool find_and_return(const BitmapKey& key, SkBitmap* result) {
         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
     }