Makes objects known to the debugger GC roots, implements the THST message, and lets DDMS request stack traces.

This fills out correct data in all columns of the "Threads" table, and
double-clicking on a thread shows that thread's stack.

Change-Id: I48f63c3612e12d35269158dc3a283f07db28c8e7
diff --git a/src/utils.h b/src/utils.h
index 66cda54..bf8191e 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -219,6 +219,9 @@
 // Returns the calling thread's tid. (The C libraries don't expose this.)
 pid_t GetTid();
 
+// Reads data from "/proc/self/task/${tid}/stat".
+void GetTaskStats(pid_t tid, int& utime, int& stime, int& task_cpu);
+
 // Sets the name of the current thread. The name may be truncated to an
 // implementation-defined limit.
 void SetThreadName(const char* name);