Debugger: ThreadHandler cleanups.

- Ask the architecture for a stack trace directly, as we only
  need the top frame.
- Properly update thread state before we go into condition
  evaluation. Otherwise, other parts of the debugger potentially
  wouldn't notice that we had continued execution in the case
  where the condition evaluates to false, and would indicate a
  program stop at the breakpoint erroneously.

src/apps/debugger/controllers/ThreadHandler.cpp

@@ -100,7 +100,6 @@ ThreadHandler::ThreadHandler(Thread* thread, Worker* worker,
 	fPreviousInstructionPointer(0),
 	fPreviousFrameAddress(0),
 	fSingleStepping(false),
-	fHasPendingConditionEvaluation(false),
 	fConditionWaitSem(-1),
 	fConditionResult(NULL)
 {
@@ -441,13 +440,6 @@ ThreadHandler::HandleCpuStateChanged()
 void
 ThreadHandler::HandleStackTraceChanged()
 {
-	AutoLocker< ::Team> teamLocker(fThread->GetTeam());
-	if (fHasPendingConditionEvaluation && fThread->GetStackTrace() != NULL) {
-		fHasPendingConditionEvaluation = false;
-		teamLocker.Unlock();
-
-		_HandleBreakpointConditionIfNeeded(fThread->GetCpuState());
-	}
 }
 
 
@@ -876,10 +868,14 @@ ThreadHandler::_HandleBreakpointConditionIfNeeded(CpuState* cpuState)
 			continue;
 
 		StackTrace* stackTrace = fThread->GetStackTrace();
+		BReference<StackTrace> stackTraceReference;
 		if (stackTrace == NULL) {
-			fThread->SetCpuState(cpuState);
-			fHasPendingConditionEvaluation = true;
-			return true;
+			if (fDebuggerInterface->GetArchitecture()->CreateStackTrace(
+				fThread->GetTeam(), this, cpuState, stackTrace, NULL, 1,
+				false, true) == B_OK) {
+				stackTraceReference.SetTo(stackTrace, true);
+			} else
+				return false;
 		}
 
 		StackFrame* frame = stackTrace->FrameAt(0);
@@ -909,6 +905,8 @@ ThreadHandler::_HandleBreakpointConditionIfNeeded(CpuState* cpuState)
 
 		BPrivate::ObjectDeleter<ExpressionJobListener> deleter(listener);
 		if (error == B_OK) {
+			_SetThreadState(THREAD_STATE_STOPPED, cpuState,
+				THREAD_STOPPED_BREAKPOINT, BString());
 			teamLocker.Unlock();
 
 			do {
@@ -934,6 +932,8 @@ ThreadHandler::_HandleBreakpointConditionIfNeeded(CpuState* cpuState)
 			if (stop)
 				return false;
 			else {
+				_SetThreadState(THREAD_STATE_RUNNING, NULL,
+					THREAD_STOPPED_UNKNOWN, BString());
 				fDebuggerInterface->ContinueThread(fThread->ID());
 				return true;
 			}