Remove all the browser side extensions code from Android.

chrome/browser/profiles/profile.cc

Index: chrome/browser/profiles/profile.cc
diff --git a/chrome/browser/profiles/profile.cc b/chrome/browser/profiles/profile.cc
index fc5cde6eaf12f7ec39f3c81ad335d405066236d4..994eb955270357e1a1eafcee8cf4f6de6eaa93a4 100644
--- a/chrome/browser/profiles/profile.cc
+++ b/chrome/browser/profiles/profile.cc
@@ -21,7 +21,6 @@
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
-#include "extensions/browser/pref_names.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/command_line.h"
@@ -33,6 +32,10 @@
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 #endif
 
+#if defined(ENABLE_EXTENSIONS)
+#include "extensions/browser/pref_names.h"
+#endif
+
 Profile::Profile()
     : restored_last_session_(false),
       sent_destroyed_notification_(false),
@@ -131,10 +134,12 @@ void Profile::RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
       prefs::kDisableExtensions,
       false,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+#if defined(ENABLE_EXTENSIONS)
   registry->RegisterBooleanPref(
       extensions::pref_names::kAlertsInitialized,
       false,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+#endif
   registry->RegisterStringPref(
       prefs::kSelectFileLastDirectory,
       std::string(),