Add a timeout option to NetworkAccessManager.

In most cases, timeouts can be applied to a reply after a request has been made.
But some APIs, such as libmygpo-qt, don't always provide access to the reply or
provide abort methods. For these cases, add an optional timeout to
NetworkAccessManager. If set, create a NetworkTimeouts instance in createRequest
and add the reply. Use the reply as the parent so that it is destroyed when the
reply is destroyed.

src/core/network.cpp

@@ -84,7 +84,12 @@ void ThreadSafeNetworkDiskCache::clear() {
 }
 
 NetworkAccessManager::NetworkAccessManager(QObject* parent)
-    : QNetworkAccessManager(parent) {
+    : QNetworkAccessManager(parent), timeout_msec_(0) {
+  setCache(new ThreadSafeNetworkDiskCache(this));
+}
+
+NetworkAccessManager::NetworkAccessManager(int timeout, QObject* parent)
+    : QNetworkAccessManager(parent), timeout_msec_(timeout) {
   setCache(new ThreadSafeNetworkDiskCache(this));
 }
 
@@ -117,7 +122,15 @@ QNetworkReply* NetworkAccessManager::createRequest(
                              QNetworkRequest::PreferCache);
   }
 
-  return QNetworkAccessManager::createRequest(op, new_request, outgoingData);
+  QNetworkReply* reply =
+      QNetworkAccessManager::createRequest(op, new_request, outgoingData);
+  if (timeout_msec_ > 0) {
+    // Since the parent is the reply, this object will be destroyed when the
+    // reply is destroyed.
+    NetworkTimeouts* timeout = new NetworkTimeouts(timeout_msec_, reply);
+    timeout->AddReply(reply);
+  }
+  return reply;
 }
 
 NetworkTimeouts::NetworkTimeouts(int timeout_msec, QObject* parent)

src/core/network.h

@@ -51,10 +51,12 @@ class NetworkAccessManager : public QNetworkAccessManager {
 
  public:
   explicit NetworkAccessManager(QObject* parent = nullptr);
+  explicit NetworkAccessManager(int timeout, QObject* parent = nullptr);
 
  protected:
   QNetworkReply* createRequest(Operation op, const QNetworkRequest& request,
                                QIODevice* outgoingData);
+  int timeout_msec_;
 };
 
 class RedirectFollower : public QObject {