chrome://accessibility: save "Internal" checkbox as preference

Saves the option to show the internal accessibility tree as the
preference kShowInternalAccessibilityTree.

Change-Id: Ib16c93f982da3e3cae1728fb8cdb0747a7463549
Reviewed-on: https://chromium-review.googlesource.com/1144271
Commit-Queue: James Wallace-Lee <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: Dominic Mazzoni <[email protected]>
Cr-Commit-Position: refs/heads/master@{#577353}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index b0d4eb0e..083de60 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -10,6 +10,7 @@
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "chrome/browser/about_flags.h"
+#include "chrome/browser/accessibility/accessibility_ui.h"
 #include "chrome/browser/accessibility/invert_bubble_prefs.h"
 #include "chrome/browser/browser_process_impl.h"
 #include "chrome/browser/chrome_content_browser_client.h"
@@ -512,6 +513,7 @@
   TRACE_EVENT0("browser", "chrome::RegisterProfilePrefs");
   SCOPED_UMA_HISTOGRAM_TIMER("Settings.RegisterProfilePrefsTime");
   // User prefs. Please keep this list alphabetized.
+  AccessibilityUIMessageHandler::RegisterProfilePrefs(registry);
   autofill::AutofillManager::RegisterProfilePrefs(registry);
   browsing_data::prefs::RegisterBrowserUserPrefs(registry);
   certificate_transparency::prefs::RegisterPrefs(registry);