Store USB device permissions in website settings.

chrome/browser/usb/usb_permission_context.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_USB_USB_PERMISSION_CONTEXT_H_
+#define CHROME_BROWSER_USB_USB_PERMISSION_CONTEXT_H_
+
+#include <map>
+#include <set>
+#include <string>
+
+#include "base/scoped_observer.h"
+#include "chrome/browser/permissions/chooser_permission_context_base.h"
+#include "device/usb/usb_service.h"
+
+class HostContentSettingsMap;
+
+class UsbPermissionContext : public ChooserPermissionContextBase,
+                             public device::UsbService::Observer {
+ public:
+  explicit UsbPermissionContext(Profile* profile);

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

For thought: Would it be possible to implement this in a way where we don't need
a separate subclass for each chooser permission? Could we always have a map of
origin+guid to setting?

What things might vary across different chooser permissions? 

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

Each chooser permission may define the properties that define an object
differently. For example, a USB device is a vendor ID, product ID and serial
number. A Bluetooth device is likely something similar but not exactly the same.
The GUID used in UsbPermissionContext is a temporary identifier assigned by
Chrome. It isn't the same if the device is reconnected.

+  ~UsbPermissionContext() override;
+
+  void GrantDevicePermission(const GURL& origin, const std::string& guid);
+  void RevokeDevicePermission(const GURL& origin, const std::string& guid);
+  bool HasDevicePermission(const GURL& origin, const std::string& guid);
+
+ protected:
+  bool IsRestrictedToSecureOrigins() const override;
+
+ private:
+  // device::UsbService::Observer implementation.
+  void OnDeviceRemoved(scoped_refptr<device::UsbDevice> device) override;
+
+  HostContentSettingsMap* host_content_settings_map_;
+  std::map<GURL, std::set<std::string>> ephemeral_devices_;
+  device::UsbService* usb_service_;
+  ScopedObserver<device::UsbService, device::UsbService::Observer> observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(UsbPermissionContext);
+};
+
+#endif  // CHROME_BROWSER_USB_USB_PERMISSION_CONTEXT_H_