[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/sharesheet/sharesheet_service_delegate.h b/chrome/browser/sharesheet/sharesheet_service_delegate.h
index dfea0d51..1257f8f 100644
--- a/chrome/browser/sharesheet/sharesheet_service_delegate.h
+++ b/chrome/browser/sharesheet/sharesheet_service_delegate.h
@@ -44,13 +44,13 @@
   void ShowBubble(std::vector<TargetInfo> targets,
                   apps::mojom::IntentPtr intent,
                   sharesheet::CloseCallback close_callback);
-  void OnBubbleClosed(const base::string16& active_action);
-  void OnTargetSelected(const base::string16& target_name,
+  void OnBubbleClosed(const std::u16string& active_action);
+  void OnTargetSelected(const std::u16string& target_name,
                         const TargetType type,
                         apps::mojom::IntentPtr intent,
                         views::View* share_action_view);
   void OnActionLaunched();
-  const gfx::VectorIcon* GetVectorIcon(const base::string16& display_name);
+  const gfx::VectorIcon* GetVectorIcon(const std::u16string& display_name);
   gfx::NativeWindow GetNativeWindow();
 
   // SharesheetController overrides
@@ -65,7 +65,7 @@
   // SharesheetServiceDelegate.
   gfx::NativeWindow native_window_;
 
-  base::string16 active_action_;
+  std::u16string active_action_;
   std::unique_ptr<SharesheetBubbleView> sharesheet_bubble_view_;
   SharesheetService* sharesheet_service_;
 };