[VK] Remove unused friend declaration in KeyboardController.

In a previous patch, we removed KeyboardLayoutManager's dependency
on KeyboardController's SetContainerType. This means that the friend
declaration in KeyboardController is no longer needed.

TBR=blakeo@chromium.org

Bug: 845780
Change-Id: I56ea22d989dcefc3bc70d4ca054678fd52c5bef7
Reviewed-on: https://chromium-review.googlesource.com/1146139Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577101}

ui/keyboard/keyboard_controller.h

@@ -235,9 +235,6 @@ class KEYBOARD_EXPORT KeyboardController
   // For access to Observer methods for simulation.
   friend class KeyboardControllerTest;
 
-  // For access to SetContainerBounds.
-  friend class KeyboardLayoutManager;
-
   // For access to NotifyKeyboardConfigChanged
   friend bool keyboard::UpdateKeyboardConfig(
       const keyboard::KeyboardConfig& config);