Instead of using -1 for pid and uid in the simulator, and then having
to special-case the simulator case all over the framework, just use
getuid and getpid, and intercept those in the simulator wrapper.

IPCThreadState.cpp

diff --git a/IPCThreadState.cpp b/IPCThreadState.cpp
index c3889e9..c371a23 100644
--- a/IPCThreadState.cpp
+++ b/IPCThreadState.cpp
@@ -366,13 +366,8 @@
 
 void IPCThreadState::clearCaller()
 {
-    if (mProcess->supportsProcesses()) {
-        mCallingPid = getpid();
-        mCallingUid = getuid();
-    } else {
-        mCallingPid = -1;
-        mCallingUid = -1;
-    }
+    mCallingPid = getpid();
+    mCallingUid = getuid();
 }
 
 void IPCThreadState::flushCommands()