Add support for navigator.webkitPersistentStorage.requestQuota

See #3010

doc/changelog.asciidoc

@@ -34,6 +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).
 
 Changed
 ~~~~~~~

doc/help/settings.asciidoc

@@ -144,6 +144,7 @@
 |<<content.netrc_file,content.netrc_file>>|Netrc-file for HTTP authentication.
 |<<content.notifications,content.notifications>>|Allow websites to show notifications.
 |<<content.pdfjs,content.pdfjs>>|Allow pdf.js to view PDF files in the browser.
+|<<content.persistent_storage,content.persistent_storage>>|Allow websites to request persistent storage quota via `navigator.webkitPersistentStorage.requestQuota`.
 |<<content.plugins,content.plugins>>|Enable plugins in Web pages.
 |<<content.print_element_backgrounds,content.print_element_backgrounds>>|Draw the background color and images also when the page is printed.
 |<<content.private_browsing,content.private_browsing>>|Open new windows in private browsing mode which does not record visited pages.
@@ -1857,6 +1858,24 @@ Default: +pass:[false]+
 
 This setting is only available with the QtWebKit backend.
 
+[[content.persistent_storage]]
+=== content.persistent_storage
+Allow websites to request persistent storage quota via `navigator.webkitPersistentStorage.requestQuota`.
+
+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.plugins]]
 === content.plugins
 Enable plugins in Web pages.

qutebrowser/browser/webengine/webenginetab.py

@@ -1046,6 +1046,17 @@ class WebEngineTab(browsertab.AbstractTab):
                 # aborted after a loadStarted signal.
                 pass
 
+    @pyqtSlot('QWebEngineQuotaRequest')
+    def _on_quota_requested(self, request):
+        size = utils.format_size(request.requestedSize())
+        shared.feature_permission(
+            url=request.origin(),
+            option='content.persistent_storage',
+            msg='use {} of persistent storage'.format(size),
+            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."""
@@ -1204,6 +1215,11 @@ class WebEngineTab(browsertab.AbstractTab):
         page.navigation_request.connect(self._on_navigation_request)
         page.featurePermissionRequested.connect(
             self._on_feature_permission_requested)
+        try:
+            page.quotaRequested.connect(self._on_quota_requested)
+        except AttributeError:
+            # Added in Qt 5.11
+            pass
 
         view.titleChanged.connect(self.title_changed)
         view.urlChanged.connect(self._on_url_changed)

qutebrowser/config/configdata.yml

@@ -598,6 +598,15 @@ content.pdfjs:
     Note that the files can still be downloaded by clicking the download button
     in the pdf.js viewer.
 
+content.persistent_storage:
+  default: ask
+  type: BoolAsk
+  backend:
+    QtWebKit: false
+    QtWebEngine: Qt 5.11
+  desc: Allow websites to request persistent storage quota via
+    `navigator.webkitPersistentStorage.requestQuota`.
+
 content.plugins:
   default: false
   type: Bool