Avoid direct use of QuasiAtomic by using Atomic.

Change-Id: I92d0f822cddb2085de7cbb4c44c3a429081892a2
diff --git a/runtime/jdwp/jdwp.h b/runtime/jdwp/jdwp.h
index 325b089..8fd07cc 100644
--- a/runtime/jdwp/jdwp.h
+++ b/runtime/jdwp/jdwp.h
@@ -339,7 +339,7 @@
   ConditionVariable attach_cond_ GUARDED_BY(attach_lock_);
 
   // Time of last debugger activity, in milliseconds.
-  int64_t last_activity_time_ms_;
+  Atomic<int64_t> last_activity_time_ms_;
 
   // Global counters and a mutex to protect them.
   AtomicInteger request_serial_;
diff --git a/runtime/jdwp/jdwp_handler.cc b/runtime/jdwp/jdwp_handler.cc
index 05bfe0d..b9379f5 100644
--- a/runtime/jdwp/jdwp_handler.cc
+++ b/runtime/jdwp/jdwp_handler.cc
@@ -1671,7 +1671,7 @@
      * so waitForDebugger() doesn't return if we stall for a bit here.
      */
     Dbg::GoActive();
-    QuasiAtomic::Write64(&last_activity_time_ms_, 0);
+    last_activity_time_ms_.StoreSequentiallyConsistent(0);
   }
 
   /*
@@ -1751,7 +1751,7 @@
    * the initial setup.  Only update if this is a non-DDMS packet.
    */
   if (request.GetCommandSet() != kJDWPDdmCmdSet) {
-    QuasiAtomic::Write64(&last_activity_time_ms_, MilliTime());
+    last_activity_time_ms_.StoreSequentiallyConsistent(MilliTime());
   }
 
   /* tell the VM that GC is okay again */
diff --git a/runtime/jdwp/jdwp_main.cc b/runtime/jdwp/jdwp_main.cc
index 64e9f37..7795b7c 100644
--- a/runtime/jdwp/jdwp_main.cc
+++ b/runtime/jdwp/jdwp_main.cc
@@ -577,7 +577,7 @@
     return -1;
   }
 
-  int64_t last = QuasiAtomic::Read64(&last_activity_time_ms_);
+  int64_t last = last_activity_time_ms_.LoadSequentiallyConsistent();
 
   /* initializing or in the middle of something? */
   if (last == 0) {