delete contents in destructor and add missing mutexes

python/core/qgsnetworkcontentfetcherregistry.sip.in

@@ -39,6 +39,8 @@ FetchedContent holds useful information about a network content being fetched
 %Docstring
 Constructs a FetchedContent with pointer to the downloaded file and status of the download
 %End
+    ~QgsFetchedContent();
+
 
 
     const QString filePath() const;

src/core/qgsnetworkcontentfetcherregistry.cpp

@@ -30,8 +30,7 @@ QgsNetworkContentFetcherRegistry::~QgsNetworkContentFetcherRegistry()
   QMap<QUrl, QgsFetchedContent *>::const_iterator it = mFileRegistry.constBegin();
   for ( ; it != mFileRegistry.constEnd(); ++it )
   {
-    it.value()->mFile->close();
-    delete it.value()->mFile;
+    delete it.value();
   }
   mFileRegistry.clear();
 }
@@ -136,6 +135,7 @@ const QFile *QgsNetworkContentFetcherRegistry::localFile( const QString &filePat
 
   if ( !QUrl::fromUserInput( filePathOrUrl ).isLocalFile() )
   {
+    QMutexLocker locker( &mMutex );
     if ( mFileRegistry.contains( QUrl( path ) ) )
     {
       const QgsFetchedContent *content = mFileRegistry.value( QUrl( path ) );
@@ -166,6 +166,7 @@ QString QgsNetworkContentFetcherRegistry::localPath( const QString &filePathOrUr
 
   if ( !QUrl::fromUserInput( filePathOrUrl ).isLocalFile() )
   {
+    QMutexLocker locker( &mMutex );
     if ( mFileRegistry.contains( QUrl( path ) ) )
     {
       const QgsFetchedContent *content = mFileRegistry.value( QUrl( path ) );

src/core/qgsnetworkcontentfetcherregistry.h

@@ -57,6 +57,12 @@ class CORE_EXPORT QgsFetchedContent : public QObject
     explicit QgsFetchedContent( QTemporaryFile *file = nullptr, ContentStatus status = NotStarted )
       : QObject(), mFile( file ), mStatus( status ) {}
 
+    ~QgsFetchedContent()
+    {
+      mFile->close();
+      delete mFile;
+    }
+
 
 #ifndef SIP_RUN
     //! Return a pointer to the local file, a null pointer if the file is not accessible yet.