[LSC] Replace base::string16 with std::u16string in //cr/browser/[h-z]*

This change replaces base::string16 with std::u16string in
//chrome/browser/[h-z]*.

Reproduction steps:
$ git grep -lw 'base::string16' chrome/browser/[h-z]* | \
      xargs sed -i 's/\bbase::string16\b/std::u16string/g'
$ git cl format

Bug: 1184339
Change-Id: Ibb73866fc5c9171ba525a1fd7dc9b4b7e619468d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2752228
Commit-Queue: Jan Wilken Dörrie <[email protected]>
Owners-Override: Peter Kasting <[email protected]>
Reviewed-by: Peter Kasting <[email protected]>
Cr-Commit-Position: refs/heads/master@{#862036}
diff --git a/chrome/browser/usb/usb_chooser_controller.h b/chrome/browser/usb/usb_chooser_controller.h
index 7641c4aa..826a31d8 100644
--- a/chrome/browser/usb/usb_chooser_controller.h
+++ b/chrome/browser/usb/usb_chooser_controller.h
@@ -36,12 +36,12 @@
   ~UsbChooserController() override;
 
   // ChooserController:
-  base::string16 GetNoOptionsText() const override;
-  base::string16 GetOkButtonLabel() const override;
-  std::pair<base::string16, base::string16> GetThrobberLabelAndTooltip()
+  std::u16string GetNoOptionsText() const override;
+  std::u16string GetOkButtonLabel() const override;
+  std::pair<std::u16string, std::u16string> GetThrobberLabelAndTooltip()
       const override;
   size_t NumOptions() const override;
-  base::string16 GetOption(size_t index) const override;
+  std::u16string GetOption(size_t index) const override;
   bool IsPaired(size_t index) const override;
   void Select(const std::vector<size_t>& indices) override;
   void Cancel() override;
@@ -68,9 +68,9 @@
       observer_;
 
   // Each pair is a (device guid, device name).
-  std::vector<std::pair<std::string, base::string16>> devices_;
+  std::vector<std::pair<std::string, std::u16string>> devices_;
   // Maps from device name to number of devices.
-  std::unordered_map<base::string16, int> device_name_map_;
+  std::unordered_map<std::u16string, int> device_name_map_;
   base::WeakPtrFactory<UsbChooserController> weak_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(UsbChooserController);