Use a consume load in SkLazyPtr.

src/ports/SkBarriers_arm.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBarriers_arm_DEFINED
 #define SkBarriers_arm_DEFINED
 
 static inline void sk_compiler_barrier() { asm volatile("" : : : "memory"); }
 
 template <typename T>
 T sk_acquire_load(T* ptr) {
     T val = *ptr;
     __sync_synchronize();  // Issue a full barrier, which is an overkill acquire barrier.
     return val;
 }
 
 template <typename T>
+T sk_consume_load(T* ptr) {
+    T val = *ptr;
+    // Unlike acquire, consume loads (data-dependent loads) are guaranteed not to reorder on ARM.
+    // No memory barrier is needed, so we just use a compiler barrier.
+    // C.f. http://preshing.com/20140709/the-purpose-of-memory_order_consume-in-cpp11/
+    sk_compiler_barrier();
+    return val;
+}
+
+template <typename T>
 void sk_release_store(T* ptr, T val) {
     __sync_synchronize();  // Issue a full barrier, which is an overkill release barrier.
     *ptr = val;
 }
 
 #endif//SkBarriers_x86_DEFINED