Generate key data before download is requested.

Once ExportKeyStreamResource::handleRequest is entered, a 'Save As'
dialog will be opened by the browser, even if key data is empty. This
may happen if passphrase is wrong.

If key data is generated before the download is actually requested, we
can check if there is anything to push to browser and prevent the
download request.

KeyringIO.h

@@ -53,7 +53,7 @@ private:
     WPushButton * m_btnCreate;
     WPushButton * m_btnExport;
     WLineEdit * m_leSearch;
-    
+
     // Used to disconnect m_btnExport from previous slot.
     Signals::connection m_exportSecretConnection;
 
@@ -122,9 +122,11 @@ private:
 class ExportKeyStreamResource : public WStreamResource
 {
 public:
-    ExportKeyStreamResource(const WString& fpr, bool isSecret,
+    ExportKeyStreamResource(const string& keyData,
+                            const WString& fpr,
                             TransientMessageWidget * tmw);
-    ExportKeyStreamResource(const WString& fpr, bool isSecret,
+    ExportKeyStreamResource(const string& keyData,
+                            const WString& fpr,
                             const string& mimeType,
                             TransientMessageWidget * tmw);
     virtual ~ExportKeyStreamResource();
@@ -135,15 +137,10 @@ public:
      */
     void handleRequest(const Http::Request& request,
                        Http::Response& response) override;
-    void SetPassphrase(const WString& passphrase)
-    {
-        m_passphrase = passphrase;
-    }
 
 private:
     WString m_fpr;
-    bool m_isSecret;
-    WString m_passphrase;
+    string m_keyData;
     TransientMessageWidget * m_tmwMessage;
 };