Debugger[New CDB]: Add support for "Select Widget to Watch".

in stopped state. Add helper for executing calls
to ExtensionContext including recording of output in
OutputCallback. Extend symbol resolution to return addresses
as well since QApplication::widgetAt() is ambiguous and needs
to be called by address. Add 'widgetat' extension command
to return the widget.

src/plugins/debugger/cdb/cdbengine.h

@@ -89,6 +89,7 @@ public:
     virtual void updateWatchData(const WatchData &data,
                                  const WatchUpdateFlags & flags = WatchUpdateFlags());
     virtual unsigned debuggerCapabilities() const;
+    virtual void watchPoint(const QPoint &);
     virtual void setRegisterValue(int regnr, const QString &value);
 
     virtual void executeStep();
@@ -150,7 +151,12 @@ private slots:
     void operateByInstructionTriggered(bool);
 
 private:
-    enum SpecialStopMode { NoSpecialStop, SpecialStopSynchronizeBreakpoints };
+    enum SpecialStopMode
+    {
+        NoSpecialStop,
+        SpecialStopSynchronizeBreakpoints,
+        SpecialStopGetWidgetAt
+    };
 
     unsigned examineStopReason(const QByteArray &messageIn, QString *message,
                                QString *exceptionBoxMessage);
@@ -166,6 +172,7 @@ private:
     inline bool isCdbProcessRunning() const { return m_process.state() != QProcess::NotRunning; }
     bool canInterruptInferior() const;
     void syncOperateByInstruction(bool operateByInstruction);
+    void postWidgetAtCommand();
 
     // Builtin commands
     void dummyHandler(const CdbBuiltinCommandPtr &);
@@ -182,6 +189,7 @@ private:
     void handleRegisters(const CdbExtensionCommandPtr &reply);
     void handleModules(const CdbExtensionCommandPtr &reply);
     void handleMemory(const CdbExtensionCommandPtr &);
+    void handleWidgetAt(const CdbExtensionCommandPtr &);
 
     QString normalizeFileName(const QString &f);
     void updateLocalVariable(const QByteArray &iname);
@@ -215,6 +223,8 @@ private:
     QByteArray m_extensionMessageBuffer;
     bool m_sourceStepInto;
     unsigned m_wX86BreakpointCount;
+    int m_watchPointX;
+    int m_watchPointY;
 };
 
 } // namespace Internal