[VK] Remove extraneous comment.

Follow up on r1124735.

TBR=blakeo@chromium.org

Bug: 845780
Change-Id: If2e40e0884fe46f5cf874f5eb5d1aeb4e479c722
Reviewed-on: https://chromium-review.googlesource.com/1130199Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573488}

ui/keyboard/keyboard_controller.h

@@ -225,7 +225,6 @@ class KEYBOARD_EXPORT KeyboardController
       ui::InputMethodKeyboardControllerObserver* observer) override;
   void RemoveObserver(
       ui::InputMethodKeyboardControllerObserver* observer) override;
-  // Returns true if keyboard is in a SHOWN state.
   bool IsKeyboardVisible() override;
 
  private: