Framework-side support for Dalvik "isSensitiveThread" hook.

Used in lock contention stats.

Bug: 3226270
Change-Id: Ie6f58d130a29079a59bdefad40b80304d9bc3623
diff --git a/include/binder/IPCThreadState.h b/include/binder/IPCThreadState.h
index b54718f..3378d97 100644
--- a/include/binder/IPCThreadState.h
+++ b/include/binder/IPCThreadState.h
@@ -33,6 +33,7 @@
 {
 public:
     static  IPCThreadState*     self();
+    static  IPCThreadState*     selfOrNull();  // self(), but won't instantiate
     
             sp<ProcessState>    process();