Fix private methods and comments

AssistiveWindowControllerImpl is not called directly but called through
ImeAssistiveWindowHandlerInterface so its overridden methods do not need
to be public.
Also remove extra comment and variable.

No-Bug: Clean Up
Change-Id: I51e9df427d937c12e26d0b2fed63f16619bdbfa3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2153176Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: My Nguyen <myy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759895}

chrome/browser/chromeos/input_method/assistive_window_controller_impl.h

@@ -29,6 +29,7 @@ class AssistiveWindowControllerImpl
   AssistiveWindowControllerImpl();
   ~AssistiveWindowControllerImpl() override;
 
+ private:
   // IMEAssistiveWindowHandlerInterface implementation.
   void SetBounds(const gfx::Rect& cursor_bounds) override;
   void ShowSuggestion(const base::string16& text,
@@ -41,10 +42,7 @@ class AssistiveWindowControllerImpl
 
   void Init();
 
-  // The suggestion window view.
   ui::ime::SuggestionWindowView* suggestion_window_view_ = nullptr;
-
-  bool is_focused_ = false;
   base::string16 suggestion_text_;
 
   DISALLOW_COPY_AND_ASSIGN(AssistiveWindowControllerImpl);