Implement tab indicator for WebUSB.

chrome/browser/usb/usb_tab_helper.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_TAB_HELPER_H_
 #define CHROME_BROWSER_USB_USB_TAB_HELPER_H_
 
 #include <map>
 
 #include "base/macros.h"
@@ skipping 24 matching lines @@
   ~UsbTabHelper() override;
 
   void CreateDeviceManager(
       content::RenderFrameHost* render_frame_host,
       mojo::InterfaceRequest<device::usb::DeviceManager> request);
 
   void CreateChooserService(
       content::RenderFrameHost* render_frame_host,
       mojo::InterfaceRequest<device::usb::ChooserService> request);
 
+  void IncrementConnectionCount();
+  void DecrementConnectionCount();
+  bool IsDeviceConnected() const;
+
  private:
   explicit UsbTabHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<UsbTabHelper>;
 
   // content::WebContentsObserver overrides:
   void RenderFrameDeleted(content::RenderFrameHost* render_frame_host) override;
 
   FrameUsbServices* GetFrameUsbService(
       content::RenderFrameHost* render_frame_host);
 
   base::WeakPtr<device::usb::PermissionProvider> GetPermissionProvider(
       content::RenderFrameHost* render_frame_host);
 
   void GetChooserService(
       content::RenderFrameHost* render_frame_host,
       mojo::InterfaceRequest<device::usb::ChooserService> request);
 
+  void NotifyTabStateChanged() const;
+
   FrameUsbServicesMap frame_usb_services_;
+  int device_connection_count_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbTabHelper);
 };
 
 #endif  // CHROME_BROWSER_USB_USB_TAB_HELPER_H_