If Ashmem cache fails pinCache, do not reallocate.

include/lazy/SkImageCache.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageCache_DEFINED
 #define SkImageCache_DEFINED
 
@@ skipping 16 matching lines @@
      *  @return Pointer to the newly allocated memory, or NULL. This memory is safe to use until
      *          releaseCache is called with ID.
      */
     virtual void* allocAndPinCache(size_t bytes, intptr_t* ID) = 0;
 
     /**
      *  Re-request the memory associated with ID.
      *  @param ID Unique ID for the memory block.
      *  @return Pointer: If non-NULL, points to the previously allocated memory, in which case
      *          this call must be balanced with a call to releaseCache. If NULL, the memory
-     *          has been reclaimed, so allocAndPinCache must be called again, and ID is no
-     *          longer valid (thus throwAwayCache need not be called).
+     *          has been reclaimed, so allocAndPinCache must be called again with a pointer to
+     *          the same ID.
      */
     virtual void* pinCache(intptr_t ID) = 0;
 
     /**
      *  Inform the cache that it is safe to free the block of memory corresponding to ID. After
-     *  calling this function, the pointer returnted by allocAndPinCache or pinCache must not be
-     *  used again. In order to access the same memory after this, pinCache must be called.
+     *  calling this function, the pointer returned by allocAndPinCache or pinCache must not be
+     *  used again. In order to access the same memory after this, pinCache must be called with
+     *  the same ID.
      *  @param ID Unique ID for the memory block which is now safe to age out of the cache.
      */
     virtual void releaseCache(intptr_t ID) = 0;
 
     /**
      *  Inform the cache that the block of memory associated with ID will not be asked for again.
      *  After this call, ID is no longer valid. Must not be called while the associated memory is
-     *  pinned. Must be called to balance a successful allocAndPinCache, unless a later pinCache
-     *  returns NULL.
+     *  pinned. Must be called to balance a successful allocAndPinCache.
      */
     virtual void throwAwayCache(intptr_t ID) = 0;
 
     /**
      *  ID which does not correspond to any valid cache.
      */
     static const intptr_t UNINITIALIZED_ID = 0;
 
 #ifdef SK_DEBUG
     enum CacheStatus {
         kPinned_CacheStatus,
         kUnpinned_CacheStatus,
         kThrownAway_CacheStatus,
     };
 
     /**
      *  Debug only function to get the status of a particular block of memory.
      */
     virtual CacheStatus getCacheStatus(intptr_t ID) const = 0;
 #endif
 };
 #endif // SkImageCache_DEFINED