Store USB device permissions in website settings.

chrome/browser/permissions/chooser_permission_context_base.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_PERMISSIONS_CHOOSER_PERMISSION_CONTEXT_BASE_H_
+#define CHROME_BROWSER_PERMISSIONS_CHOOSER_PERMISSION_CONTEXT_BASE_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/permissions/permission_context_base.h"
+
+namespace base {
+class DictionaryValue;
+class ListValue;
+class Value;
+}
+
+class ChooserPermissionContextBase : public PermissionContextBase {

[raymes, 2015/10/06 05:28:20]

Mounir should have some thoughts about inheriting from PermissionContextBase so
reach out to him for comments. In general I feel it's a reasonable direction to
head in but some functions won't be meaningful
(RequestPermission/ResetPermission/Cancel). Those things only really apply to
non-chooser permissions. We would need to rework the code to make that clear.

In support of this direction though, I'm starting to feel more strongly about
allowing permissions which are only queryable (not requestable) in the
permissions API. e.g. having a way to see if the usb/bluetooth permission is
globally on/off for a site would be useful. Mounir may have a different opinion
though :)

[Reilly Grant (use Gerrit), 2015/10/06 20:45:30]

Alright.

+ public:
+  ChooserPermissionContextBase(Profile* profile,
+                               ContentSettingsType permission_type);
+  ~ChooserPermissionContextBase() override;
+
+  scoped_ptr<base::ListValue> GetChosenObjects(const GURL& origin);

[raymes, 2015/10/06 05:28:20]

How is an "Object" defined?

Would GetPreviouslyChosenObjects be more descriptive here?

[Reilly Grant (use Gerrit), 2015/10/06 20:45:30]

An object is defined by the subclass. For the benefit of the site-settings UI we
will need to do define a way to translate an object into a user visible item
that can be individually revoked. Otherwise it's an opaque bag of properties
that the particular ChooserPermissionContextBase implementation assigns meaning
to.
Done.

[raymes, 2015/10/07 04:48:29]

Could we impose some structure on it? This might make doing generic things (like
UI) easier down the track. e.g. could we refer to these as "devices" -
GetChosenDevices (could we envision a time when this wouldn't be a device?).
Could ensure the return value is a simple dictionary of string:string? Thoughts?

[Bernhard Bauer, 2015/10/12 11:03:48]

Yes -- for example, a chooser-based geolocation prompt might allow the user to
select a location granularity, not a particular device.

[Reilly Grant (use Gerrit), 2015/10/12 15:37:48]

My followup UI patch adds a virtual GetStringToDisplayForObject() method on this
class that will convert a base::Value into a string to display in the UI. It
also adds a virtual IsValidObject() method that subclasses can use to ensure
that the values read from WebsiteSettings are well formed. I think I'll merge
that part of the patch back into this one so you can see more of where I'm going
with this.

+  void GrantObjectPermission(const GURL& origin,

[raymes, 2015/10/06 05:28:20]

Perhaps we should pass the top level and requesting origins in to these
functions

[Reilly Grant (use Gerrit), 2015/10/06 20:45:30]

Done.

+                             scoped_ptr<base::Value> object);
+  void RevokeObjectPermission(const GURL& origin, const base::Value& object);
+
+ private:
+  scoped_ptr<base::DictionaryValue> GetWebsiteSetting(const GURL& origin);
+  void SetWebsiteSetting(const GURL& origin, scoped_ptr<base::Value> value);
+};
+
+#endif  // CHROME_BROWSER_PERMISSIONS_CHOOSER_PERMISSION_CONTEXT_BASE_H_