IDocument: Make mimeType a value member

Change-Id: I2e90ccf0a45ae8d00bcd00ec77fe0d9776f2f119
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/genericprojectmanager/genericproject.cpp

@@ -409,6 +409,7 @@ GenericProjectFile::GenericProjectFile(GenericProject *parent, QString fileName,
       m_options(options)
 {
     setId("Generic.ProjectFile");
+    setMimeType(QLatin1String(Constants::GENERICMIMETYPE));
     setFilePath(fileName);
 }
 
@@ -427,11 +428,6 @@ QString GenericProjectFile::suggestedFileName() const
     return QString();
 }
 
-QString GenericProjectFile::mimeType() const
-{
-    return QLatin1String(Constants::GENERICMIMETYPE);
-}
-
 bool GenericProjectFile::isModified() const
 {
     return false;