Move c/b/chromeos/customization_* into c/b/chromeos/customization

In favor of less files to have directly under c/b/chromeos.
This change was created mechanically as follows:

% cd chrome/browser/chromeos
% mkdir customization
% git mv customization_* customization
% cd -
% tools/git/mass-rename.sh
% tools/git/for-all-touched-files.py -c "tools/sort-headers.py -f [[FILENAME]]"

BUG=none
TEST=things build as before
[email protected]

Review URL: https://codereview.chromium.org/768053002

Cr-Commit-Position: refs/heads/master@{#306554}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index a19a01e..8b4cdb0a 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -156,7 +156,7 @@
 #include "chrome/browser/chromeos/app_mode/kiosk_app_manager.h"
 #include "chrome/browser/chromeos/attestation/platform_verification_flow.h"
 #include "chrome/browser/chromeos/audio/audio_devices_pref_handler_impl.h"
-#include "chrome/browser/chromeos/customization_document.h"
+#include "chrome/browser/chromeos/customization/customization_document.h"
 #include "chrome/browser/chromeos/display/display_preferences.h"
 #include "chrome/browser/chromeos/extensions/echo_private_api.h"
 #include "chrome/browser/chromeos/file_system_provider/registry.h"