Let inspector know about on-the-record profiles.

The developer tools only saves preferences to disk, and reads them from
disk, if the profile of the page they are drawing to isn't
off-the-record. So if you want it to remember your dark mode preference
the page hosting the inspector needs to be linked to an on-the-record
profile. So we need to create a new page linked to a specific profile
and then set that on the view.

Options at this point:
1. (in `__init__()` always make a new page linked to the qute default
   profile and add that to the view
2. delay creating the view and page until `inspect()` is called and get
   a pointer to the profile of the page being inspected

(1) is actually what we have done on previous Qt versions because there
the inspector was started with WebEngine's default, global, profile,
which used to be on-the-record. I'm not sure if there are any specific
ramifications to having the inspector data persistent when the page it
is attached to isn't, but there might be stuff like per-domain
preferences saved in that case which would be an information leak.

So I've went with (2) even though it is probably going to be more
disruptive to the tests. In the future if we re-use inspectors across
different tabs/windows again we can make a new page on demand if the
profile of the inspected page differs form the initial one. For now I've
put an assert there because I am lazy.

It's a bit awkward having most of the setup in `inspect()` and not
`__init__()`. `_init_inspector()` and `inspect()` are only ever called
once right beside each other though (now) so we could just pass the page
to `__init__()` and get rid of `inspect()`.

1 files changed, 15 insertions, 7 deletions

diff --git a/qutebrowser/browser/webengine/webengineinspector.py b/qutebrowser/browser/webengine/webengineinspector.py
index 7ad51fd7b..bb19ef153 100644
--- a/qutebrowser/browser/webengine/webengineinspector.py
+++ b/qutebrowser/browser/webengine/webengineinspector.py
@@ -62,13 +62,7 @@ class WebEngineInspector(inspector.AbstractWebInspector):
                  parent: QWidget = None) -> None:
         super().__init__(splitter, win_id, parent)
         self._check_devtools_resources()
-
-        view = WebEngineInspectorView()
-        self._settings = webenginesettings.WebEngineSettings(view.settings())
-        self._set_widget(view)
-        page = view.page()
-        page.windowCloseRequested.connect(  # type: ignore[attr-defined]
-            self._on_window_close_requested)
+        self._settings = None
 
     def _on_window_close_requested(self) -> None:
         """Called when the 'x' was clicked in the devtools."""
@@ -98,7 +92,21 @@ class WebEngineInspector(inspector.AbstractWebInspector):
                                   "Fedora package.")
 
     def inspect(self, page: QWebEnginePage) -> None:  # type: ignore[override]
+        if not self._widget:
+            view = WebEngineInspectorView()
+            inspector_page = QWebEnginePage(
+                page.profile(),
+                self
+            )
+            inspector_page.windowCloseRequested.connect(  # type: ignore[attr-defined]
+                self._on_window_close_requested)
+            view.setPage(inspector_page)
+            self._settings = webenginesettings.WebEngineSettings(view.settings())
+            self._set_widget(view)
+
         inspector_page = self._widget.page()
+        assert inspector_page.profile() == page.profile()
+
         inspector_page.setInspectedPage(page)
         self._settings.update_for_url(inspector_page.requestedUrl())