Fix alignment issue on old ART runtime.

mojo/android/system/core_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/android/system/core_impl.h"
 
 #include "base/android/base_jni_registrar.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_registrar.h"
 #include "base/android/library_loader/library_loader_hooks.h"
@@ skipping 370 matching lines @@
     // If |id| is |kInvalidHandleCancelID|, the async wait was done on an
     // invalid handle, so the AsyncWaitCallback will be called and will clear
     // the data_ptr.
     return;
   }
   scoped_ptr<AsyncWaitCallbackData> deleter(
       reinterpret_cast<AsyncWaitCallbackData*>(data_ptr));
   Environment::GetDefaultAsyncWaiter()->CancelWait(id);
 }
 
+static jint GetNativeBufferOffset(JNIEnv* env,
+                                  jobject jcaller,
+                                  jobject buffer,
+                                  jint alignment) {
+  jint offset =
+      reinterpret_cast<uintptr_t>(env->GetDirectBufferAddress(buffer)) %
+      alignment;
+  if (offset == 0)
+    return 0;
+  return alignment - offset;
+}
+
 bool RegisterCoreImpl(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace android
 }  // namespace mojo