Refactor atomic integer.

Refactored atomic integer to be similar to c++11 std::atomic<int>.

Removed jdwp serial lock and reverted lock level name change from
https://googleplex-android-review.googlesource.com/#/c/327297/

Change-Id: I2229f30c4d5762a0e8c72697d6aca4683750af35
diff --git a/runtime/jdwp/jdwp_main.cc b/runtime/jdwp/jdwp_main.cc
index e831af4..8e61d23 100644
--- a/runtime/jdwp/jdwp_main.cc
+++ b/runtime/jdwp/jdwp_main.cc
@@ -36,7 +36,7 @@
  * JdwpNetStateBase class implementation
  */
 JdwpNetStateBase::JdwpNetStateBase(JdwpState* state)
-    : state_(state), socket_lock_("JdwpNetStateBase lock", kJdwpSerialSocketLock) {
+    : state_(state), socket_lock_("JdwpNetStateBase lock", kJdwpSocketLock) {
   clientSock = -1;
   wake_pipe_[0] = -1;
   wake_pipe_[1] = -1;
@@ -185,7 +185,6 @@
  * packets to the debugger.
  */
 uint32_t JdwpState::NextRequestSerial() {
-  MutexLock mu(Thread::Current(), serial_lock_);
   return request_serial_++;
 }
 
@@ -194,7 +193,6 @@
  * message type EventRequest.Set.
  */
 uint32_t JdwpState::NextEventSerial() {
-  MutexLock mu(Thread::Current(), serial_lock_);
   return event_serial_++;
 }
 
@@ -211,7 +209,6 @@
       attach_lock_("JDWP attach lock", kJdwpAttachLock),
       attach_cond_("JDWP attach condition variable", attach_lock_),
       last_activity_time_ms_(0),
-      serial_lock_("JDWP serial lock", kJdwpSerialSocketLock),
       request_serial_(0x10000000),
       event_serial_(0x20000000),
       event_list_lock_("JDWP event list lock", kJdwpEventListLock),