vcl timers: avoid crash with vcldemo.

The system timer needs earlier and/or more consistent initialization.

Change-Id: I148d98537cc055a091181bd36a654ae35f665aaf

include/vcl/timer.hxx

@@ -34,6 +34,9 @@ protected:
     virtual bool ReadyForSchedule( bool bTimer ) SAL_OVERRIDE;
     virtual sal_uInt64 UpdateMinPeriod( sal_uInt64 nMinPeriod, sal_uInt64 nTime ) SAL_OVERRIDE;
 
+private:
+    void InitSystemTimer();
+
 public:
     Timer();
     Timer( const Timer& rTimer );

vcl/source/app/timer.cxx

@@ -81,11 +81,27 @@ sal_uInt64 Timer::UpdateMinPeriod( sal_uInt64 nMinPeriod, sal_uInt64 nTime )
     return nMinPeriod;
 }
 
+/**
+ * Initialize the platform specific timer on which all the
+ * platform independent timers are built
+ */
+void Timer::InitSystemTimer()
+{
+    ImplSVData* pSVData = ImplGetSVData();
+    if( ! pSVData->mpSalTimer )
+    {
+        pSVData->mnTimerPeriod = MAX_TIMER_PERIOD;
+        pSVData->mpSalTimer = pSVData->mpDefInst->CreateSalTimer();
+        pSVData->mpSalTimer->SetCallback( CallbackTaskScheduling );
+    }
+}
+
 Timer::Timer() : Scheduler()
 {
     mnTimeout = 1;
     mbAuto = false;
     mePriority = SchedulerPriority::HIGHEST;
+    InitSystemTimer();
 }
 
 Timer::Timer( const Timer& rTimer ) : Scheduler(rTimer)
@@ -93,6 +109,7 @@ Timer::Timer( const Timer& rTimer ) : Scheduler(rTimer)
     mnTimeout = rTimer.mnTimeout;
     mbAuto = rTimer.mbAuto;
     maTimeoutHdl = rTimer.maTimeoutHdl;
+    InitSystemTimer();
 }
 
 void Timer::Invoke()
@@ -103,13 +120,9 @@ void Timer::Invoke()
 void Timer::Start()
 {
     Scheduler::Start();
-    ImplSVData*     pSVData = ImplGetSVData();
-    if( ! pSVData->mpSalTimer )
-    {
-        pSVData->mnTimerPeriod = MAX_TIMER_PERIOD;
-        pSVData->mpSalTimer = pSVData->mpDefInst->CreateSalTimer();
-        pSVData->mpSalTimer->SetCallback( CallbackTaskScheduling );
-    }
+
+    ImplSVData* pSVData = ImplGetSVData();
+    assert( pSVData->mpSalTimer != NULL );
     if ( mnTimeout < pSVData->mnTimerPeriod )
         Timer::ImplStartTimer( pSVData, mnTimeout );
 }