Add UMA for the number of devices in the chooser when a device is paired

chrome/browser/ui/bluetooth/bluetooth_chooser_controller.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_UI_BLUETOOTH_BLUETOOTH_CHOOSER_CONTROLLER_H_
 #define CHROME_BROWSER_UI_BLUETOOTH_BLUETOOTH_CHOOSER_CONTROLLER_H_
 
 #include <stddef.h>
 
 #include <string>
 #include <unordered_map>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "chrome/browser/chooser_controller/chooser_controller.h"
 #include "content/public/browser/bluetooth_chooser.h"
 
 // BluetoothChooserController is a chooser that presents a list of
 // Bluetooth device names, which come from |bluetooth_chooser_desktop_|.
 // It can be used by WebBluetooth API to get the user's permission to
 // access a Bluetooth device. It is owned by ChooserBubbleDelegate.
 class BluetoothChooserController : public ChooserController {
  public:
-  explicit BluetoothChooserController(
+  BluetoothChooserController(
       content::RenderFrameHost* owner,
       const content::BluetoothChooser::EventHandler& event_handler);
   ~BluetoothChooserController() override;
 
   // ChooserController:
   bool ShouldShowIconBeforeText() const override;
   base::string16 GetNoOptionsText() const override;
   base::string16 GetOkButtonLabel() const override;
   size_t NumOptions() const override;
   int GetSignalStrengthLevel(size_t index) const override;
@@ skipping 49 matching lines @@
   // Maps from device name to number of devices with that name.
   std::unordered_map<base::string16, int> device_name_counts_;
 
   content::BluetoothChooser::EventHandler event_handler_;
   base::string16 status_text_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothChooserController);
 };
 
 #endif  // CHROME_BROWSER_UI_BLUETOOTH_BLUETOOTH_CHOOSER_CONTROLLER_H_