Add content.autoplay option

See #3010
Closes #1643

doc/help/settings.asciidoc

@@ -109,6 +109,7 @@
 |<<completion.use_best_match,completion.use_best_match>>|Execute the best-matching command on a partial match.
 |<<completion.web_history_max_items,completion.web_history_max_items>>|Number of URLs to show in the web history.
 |<<confirm_quit,confirm_quit>>|Require a confirmation before quitting the application.
+|<<content.autoplay,content.autoplay>>|Automatically start playing `<video>` elements.
 |<<content.cache.appcache,content.cache.appcache>>|Enable support for the HTML 5 web application cache feature.
 |<<content.cache.maximum_pages,content.cache.maximum_pages>>|Maximum number of pages to hold in the global memory page cache.
 |<<content.cache.size,content.cache.size>>|Size (in bytes) of the HTTP network cache. Null to use the default value.
@@ -1467,6 +1468,19 @@ Default:
 
 - +pass:[never]+
 
+[[content.autoplay]]
+=== content.autoplay
+Automatically start playing `<video>` elements.
+Note this option needs a restart with QtWebEngine on Qt < 5.11.
+
+Type: <<types,Bool>>
+
+Default: +pass:[true]+
+
+On QtWebEngine, this setting requires Qt 5.10 or newer.
+
+On QtWebKit, this setting is unavailable.
+
 [[content.cache.appcache]]
 === content.cache.appcache
 Enable support for the HTML 5 web application cache feature.

qutebrowser/browser/webengine/webenginesettings.py

@@ -156,15 +156,19 @@ class WebEngineSettings(websettings.AbstractSettings):
         # Attributes which don't exist in all Qt versions.
         new_attributes = {
             # Qt 5.8
-            'content.print_element_backgrounds': 'PrintElementBackgrounds',
+            'content.print_element_backgrounds':
+                ('PrintElementBackgrounds', None),
+            # Qt 5.11
+            'content.autoplay':
+                ('PlaybackRequiresUserGesture', lambda val: not val),
         }
-        for name, attribute in new_attributes.items():
+        for name, (attribute, converter) in new_attributes.items():
             try:
                 value = getattr(QWebEngineSettings, attribute)
             except AttributeError:
                 continue
 
-            self._ATTRIBUTES[name] = Attr(value)
+            self._ATTRIBUTES[name] = Attr(value, converter=converter)
 
 
 class ProfileSetter:

qutebrowser/config/configdata.py

@@ -149,6 +149,7 @@ def _parse_yaml_backends_dict(name, node):
         False: False,
         'Qt 5.8': qtutils.version_check('5.8'),
         'Qt 5.9': qtutils.version_check('5.9'),
+        'Qt 5.10': qtutils.version_check('5.10'),
         'Qt 5.11': qtutils.version_check('5.11'),
     }
     for key in sorted(node.keys()):

qutebrowser/config/configdata.yml

@@ -214,6 +214,17 @@ auto_save.session:
 
 ## content
 
+content.autoplay:
+  default: true
+  type: Bool
+  backend:
+    QtWebEngine: Qt 5.10
+    QtWebKit: false
+  desc: >-
+    Automatically start playing `<video>` elements.
+
+    Note this option needs a restart with QtWebEngine on Qt < 5.11.
+
 content.cache.size:
   default: null
   type:

qutebrowser/config/configinit.py

@@ -172,7 +172,13 @@ def qt_args(namespace):
             # https://codereview.qt-project.org/#/c/217932/
             # Needed for Qt < 5.9.5 and < 5.10.1
             argv.append('--disable-shared-workers')
+
         if config.val.qt.force_software_rendering == 'chromium':
             argv.append('--disable-gpu')
 
+        if not qtutils.version_check('5.11'):
+            # On Qt 5.11, we can control this via QWebEngineSettings
+            if not config.val.content.autoplay:
+                argv.append('--autoplay-policy=user-gesture-required')
+
     return argv

tests/unit/config/test_configinit.py

@@ -359,7 +359,7 @@ class TestQtArgs:
     def patch_version_check(self, monkeypatch):
         """Make sure no --disable-shared-workers argument gets added."""
         monkeypatch.setattr(configinit.qtutils, 'version_check',
-                            lambda version, compiled: True)
+                            lambda version, compiled=False: True)
 
     @pytest.mark.parametrize('args, expected', [
         # No Qt arguments
@@ -403,7 +403,7 @@ class TestQtArgs:
     def test_shared_workers(self, config_stub, monkeypatch, parser,
                             backend, expected):
         monkeypatch.setattr(configinit.qtutils, 'version_check',
-                            lambda version, compiled: False)
+                            lambda version, compiled=False: False)
         monkeypatch.setattr(configinit.objects, 'backend', backend)
         parsed = parser.parse_args([])
         assert configinit.qt_args(parsed) == [sys.argv[0]] + expected
@@ -416,6 +416,23 @@ class TestQtArgs:
         expected = [sys.argv[0], '--disable-gpu']
         assert configinit.qt_args(parsed) == expected
 
+    @pytest.mark.parametrize('backend, new_version, autoplay, added', [
+        (usertypes.Backend.QtWebEngine, True, False, False),  # new
+        (usertypes.Backend.QtWebKit, False, False, False),  # QtWebKit
+        (usertypes.Backend.QtWebEngine, False, True, False),  # enabled
+        (usertypes.Backend.QtWebEngine, False, False, True),
+    ])
+    def test_autoplay(self, config_stub, monkeypatch, parser,
+                      backend, new_version, autoplay, added):
+        config_stub.val.content.autoplay = autoplay
+        monkeypatch.setattr(configinit.qtutils, 'version_check',
+                            lambda version, compiled=False: new_version)
+        monkeypatch.setattr(configinit.objects, 'backend', backend)
+
+        parsed = parser.parse_args([])
+        args = configinit.qt_args(parsed)
+        assert ('--autoplay-policy=user-gesture-required' in args) == added
+
 
 @pytest.mark.parametrize('arg, confval, used', [
     # overridden by commandline arg