If Ashmem cache fails pinCache, do not reallocate.

include/lazy/SkImageCache.h

Index: include/lazy/SkImageCache.h
diff --git a/include/lazy/SkImageCache.h b/include/lazy/SkImageCache.h
index 045ce2c384f168c94129408d65b67ffaa6274d14..6cd064ba5bfae6cd73672975080cf4d5d82ef318 100644
--- a/include/lazy/SkImageCache.h
+++ b/include/lazy/SkImageCache.h
@@ -34,15 +34,16 @@ public:
      *  @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;
@@ -50,8 +51,7 @@ public:
     /**
      *  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      *  After this call, ID is no longer valid.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;