debugger: centralize check for changed display entries

Change-Id: I22c58812990925102aeeb80571bb877fd0a2924b
Reviewed-on: http://codereview.qt.nokia.com/3330
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/watchdata.cpp

@@ -383,8 +383,7 @@ QString WatchData::toToolTip() const
         formatToolTipRow(str, tr("Referencing Address"),
                          QString::fromAscii(hexReferencingAddress()));
     if (size)
-        formatToolTipRow(str, tr("Size"),
-                         QString::number(size));
+        formatToolTipRow(str, tr("Size"), QString::number(size));
     formatToolTipRow(str, tr("Internal ID"), iname);
     formatToolTipRow(str, tr("Generation"),
         QString::number(generation));
@@ -437,6 +436,11 @@ QByteArray WatchData::hexReferencingAddress() const
     return QByteArray();
 }
 
+bool WatchData::hasChanged(const WatchData &old) const
+{
+    return !value.isEmpty() && value != old.value && value != msgNotInScope();
+}
+
 } // namespace Internal
 } // namespace Debugger