Add support for navigator.registerProtocolHandler

See #3010

doc/changelog.asciidoc

@@ -34,9 +34,9 @@ Added
   * New `{audio}` field for `window.title_format` and `tabs.title.format` which
     displays `[M]`/`[A]` for muted/recently audible tabs.
   * New `:tab-mute` command (bound to `<Alt-m>`) to mute/unmute a tab.
-- QtWebEngine: Support for `navigator.webkitPersistentStorage.requestQuota`
-  * New `content.persistent_storage` setting to allow/deny requests (default:
-    ask).
+- QtWebEngine: Support for new permissions, including new settings (true/false/ask):
+  * `navigator.webkitPersistentStorage.requestQuota` with a new `content.persistent_storage` setting.
+  * `navigator.registerProtocolHandler` with a new `content.register_protocol_handler` setting.
 
 Changed
 ~~~~~~~

doc/help/settings.asciidoc

@@ -150,6 +150,7 @@
 |<<content.private_browsing,content.private_browsing>>|Open new windows in private browsing mode which does not record visited pages.
 |<<content.proxy,content.proxy>>|Proxy to use.
 |<<content.proxy_dns_requests,content.proxy_dns_requests>>|Send DNS requests over the configured proxy.
+|<<content.register_protocol_handler,content.register_protocol_handler>>|Allow websites to register protocol handlers via `navigator.registerProtocolHandler`.
 |<<content.ssl_strict,content.ssl_strict>>|Validate SSL handshakes.
 |<<content.user_stylesheets,content.user_stylesheets>>|List of user stylesheet filenames to use.
 |<<content.webgl,content.webgl>>|Enable WebGL.
@@ -1930,6 +1931,24 @@ Default: +pass:[true]+
 
 This setting is only available with the QtWebKit backend.
 
+[[content.register_protocol_handler]]
+=== content.register_protocol_handler
+Allow websites to register protocol handlers via `navigator.registerProtocolHandler`.
+
+Type: <<types,BoolAsk>>
+
+Valid values:
+
+ * +true+
+ * +false+
+ * +ask+
+
+Default: +pass:[ask]+
+
+On QtWebEngine, this setting requires Qt 5.11 or newer.
+
+On QtWebKit, this setting is unavailable.
+
 [[content.ssl_strict]]
 === content.ssl_strict
 Validate SSL handshakes.

qutebrowser/browser/webengine/webenginetab.py

@@ -1057,6 +1057,16 @@ class WebEngineTab(browsertab.AbstractTab):
             abort_on=[self.shutting_down, self.load_started],
             blocking=True)
 
+    @pyqtSlot('QWebEngineRegisterProtocolHandlerRequest')
+    def _on_register_protocol_handler_requested(self, request):
+        shared.feature_permission(
+            url=request.origin(),
+            option='content.register_protocol_handler',
+            msg='open all {} links'.format(request.scheme()),
+            yes_action=request.accept, no_action=request.reject,
+            abort_on=[self.shutting_down, self.load_started],
+            blocking=True)
+
     @pyqtSlot()
     def _on_load_started(self):
         """Clear search when a new load is started if needed."""
@@ -1217,6 +1227,8 @@ class WebEngineTab(browsertab.AbstractTab):
             self._on_feature_permission_requested)
         try:
             page.quotaRequested.connect(self._on_quota_requested)
+            page.registerProtocolHandlerRequested.connect(
+                self._on_register_protocol_handler_requested)
         except AttributeError:
             # Added in Qt 5.11
             pass

qutebrowser/config/configdata.yml

@@ -644,6 +644,15 @@ content.proxy_dns_requests:
   backend: QtWebKit
   desc: Send DNS requests over the configured proxy.
 
+content.register_protocol_handler:
+  default: ask
+  type: BoolAsk
+  backend:
+    QtWebKit: false
+    QtWebEngine: Qt 5.11
+  desc: Allow websites to register protocol handlers via
+    `navigator.registerProtocolHandler`.
+
 content.ssl_strict:
   default: ask
   type: BoolAsk