Skip spinlock overhead on Android

src/gpu/batches/GrBatch.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrBatch.h"
 
 #include "GrMemoryPool.h"
 #include "SkSpinlock.h"
 
 // TODO I noticed a small benefit to using a larger exclusive pool for batches.  Its very small,
 // but seems to be mostly consistent.  There is a lot in flux right now, but we should really
 // revisit this when batch is everywhere
 
 
 // We use a global pool protected by a mutex(spinlock). Chrome may use the same GrContext on
 // different threads. The GrContext is not used concurrently on different threads and there is a
 // memory barrier between accesses of a context on different threads. Also, there may be multiple
 // GrContexts and those contexts may be in use concurrently on different threads.
 namespace {
 static SkSpinlock gBatchSpinlock;
 class MemoryPoolAccessor {
 public:
+
+// We know in the Android framework there is only one GrContext.
+#if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK)
+    MemoryPoolAccessor() {}
+    ~MemoryPoolAccessor() {}
+#else
     MemoryPoolAccessor() { gBatchSpinlock.acquire(); }
-
     ~MemoryPoolAccessor() { gBatchSpinlock.release(); }
+#endif
 
     GrMemoryPool* pool() const {
         static GrMemoryPool gPool(16384, 16384);
         return &gPool;
     }
 };
 }
 
 int32_t GrBatch::gCurrBatchClassID = GrBatch::kIllegalBatchID;
 
 int32_t GrBatch::gCurrBatchUniqueID = GrBatch::kIllegalBatchID;
 
 void* GrBatch::operator new(size_t size) {
     return MemoryPoolAccessor().pool()->allocate(size);
 }
 
 void GrBatch::operator delete(void* target) {
     return MemoryPoolAccessor().pool()->release(target);
 }
 
 GrBatch::GrBatch(uint32_t classID)
     : fClassID(classID)
     , fUniqueID(kIllegalBatchID) {
     SkASSERT(classID == SkToU32(fClassID));
     SkDEBUGCODE(fUsed = false;)
     SkDEBUGCODE(fBoundsFlags = kUninitialized_BoundsFlag);
 }
 
 GrBatch::~GrBatch() {}