Implement "GetThreadGroupParent", "Suspend", and "Resume".

This is enough to get the GUI jswat working for poking around
threads, stacks, and locals.

Change-Id: Ib02d9666cee8d39c09e4a09cf3961cebff1768ac
diff --git a/src/thread_list.h b/src/thread_list.h
index 57f9cf4..d93ec3b 100644
--- a/src/thread_list.h
+++ b/src/thread_list.h
@@ -37,9 +37,11 @@
   // Thread suspension support.
   void FullSuspendCheck(Thread* thread);
   void ResumeAll(bool for_debugger = false);
+  void Resume(Thread* thread, bool for_debugger = false);
+  void RunWhileSuspended(Thread* thread, void (*callback)(void*), void* arg);
   void SuspendAll(bool for_debugger = false);
   void SuspendSelfForDebugger();
-  void RunWhileSuspended(Thread* thread, void (*callback)(void*), void* arg);
+  void Suspend(Thread* thread, bool for_debugger = false);
   void UndoDebuggerSuspensions();
 
   // Iterates over all the threads. The caller must hold the thread list lock.
@@ -61,8 +63,6 @@
   uint32_t AllocThreadId();
   bool Contains(Thread* thread);
   void ReleaseThreadId(uint32_t id);
-  void Resume(Thread* thread);
-  void Suspend(Thread* thread);
   void SuspendAllDaemonThreads();
   void WaitForNonDaemonThreadsToExit();