Add a full screen virtual keyboard to virtual keyboard root window

ash/display/virtual_keyboard_window_controller.cc

Index: ash/display/virtual_keyboard_window_controller.cc
diff --git a/ash/display/virtual_keyboard_window_controller.cc b/ash/display/virtual_keyboard_window_controller.cc
index 098c3ce6e7e2946d7a7ef41e52b2f482ae8be487..9786aa2695f0cb5527bde0643320557050fe544c 100644
--- a/ash/display/virtual_keyboard_window_controller.cc
+++ b/ash/display/virtual_keyboard_window_controller.cc
@@ -16,6 +16,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/env.h"
 #include "ui/aura/root_window.h"
+#include "ui/keyboard/keyboard_controller.h"
 
 namespace ash {
 namespace internal {
@@ -28,6 +29,11 @@ VirtualKeyboardWindowController::~VirtualKeyboardWindowController() {
   Close();
 }
 
+void VirtualKeyboardWindowController::ActivateKeyboard(
+    keyboard::KeyboardController* keyboard_controller) {
+  root_window_controller_->ActivateKeyboard(keyboard_controller);
+}
+
 void VirtualKeyboardWindowController::UpdateWindow(
     const DisplayInfo& display_info) {
   static int virtual_keyboard_root_window_count = 0;
@@ -53,6 +59,8 @@ void VirtualKeyboardWindowController::UpdateWindow(
     root_window_controller_.reset(GetRootWindowController(
         root_window->window()));
     root_window_controller_->dispatcher()->ShowRootWindow();
+    root_window_controller_->ActivateKeyboard(
+        Shell::GetInstance()->keyboard_controller());
   } else {
     aura::RootWindow* root_window = root_window_controller_->dispatcher();
     GetRootWindowSettings(root_window->window())->display_id =