[Extensions] Move WindowController::SetFullscreenMode to browser subclass

WindowController::SetFullscreenMode() is only used by the window
controller retrieved from the Browser object, which is always a
BrowserExtensionWindowController.  Remove SetFullscreenMode() from the
base WindowController class and move it to only be on the
BrowserExtensionWindowController.

Bug: None
Change-Id: If56331ff87357fb739e5ab7858d4f56fafbddb6d
Reviewed-on: https://chromium-review.googlesource.com/1067758
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: Istiaque Ahmed <[email protected]>
Commit-Queue: Devlin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#562930}
diff --git a/chrome/browser/extensions/extension_tab_util.cc b/chrome/browser/extensions/extension_tab_util.cc
index fbfb3d7b..7dddcfe 100644
--- a/chrome/browser/extensions/extension_tab_util.cc
+++ b/chrome/browser/extensions/extension_tab_util.cc
@@ -13,6 +13,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/api/tabs/tabs_constants.h"
+#include "chrome/browser/extensions/browser_extension_window_controller.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
 #include "chrome/browser/extensions/chrome_extension_function_details.h"
 #include "chrome/browser/extensions/tab_helper.h"