Make user agent configurable

TODO

@@ -32,7 +32,6 @@ history
 Minor features
 ==============
 
-set useragent
 show current value in setting completions
 handle completion for aliases
 keybind should have completion for commands/arguments

qutebrowser/browser/webpage.py

@@ -22,6 +22,7 @@ from PyQt5.QtNetwork import QNetworkReply
 from PyQt5.QtWebKitWidgets import QWebPage
 
 import qutebrowser.utils.url as urlutils
+import qutebrowser.config.config as config
 from qutebrowser.network.networkmanager import NetworkManager
 from qutebrowser.utils.misc import read_file
 
@@ -69,6 +70,14 @@ class BrowserPage(QWebPage):
             title=title, url=urlstr, error=info.errorString, icon='')
         return True
 
+    def userAgentForUrl(self, url):
+        """Override QWebPage::userAgentForUrl to customize the user agent."""
+        ua = config.get('network', 'user-agent')
+        if not ua:
+            return super().userAgentForUrl(url)
+        else:
+            return ua
+
     def supportsExtension(self, ext):
         """Override QWebPage::supportsExtension to provide error pages.
 

qutebrowser/config/configdata.py

@@ -201,6 +201,10 @@ DATA = OrderedDict([
         ('accept-language',
          SettingValue(types.String(), 'en-US,en'),
          "Value to send in the accept-language header."),
+
+        ('user-agent',
+         SettingValue(types.String(), ''),
+         "User agent to send. Empty to send the default."),
     )),
 
     ('completion', sect.KeyValue(