Move FeatureSwitch to top-level extensions/

Move FeatureSwitch to extensions/common/
Move the switches used in FeatureSwitch to extensions/common/switches.h (when necessary).
Update some uses of the switches to use feature switch instead of the commandline

BUG=159265
[email protected] (c/b/download)
[email protected] (c/b/ui/, c/test/ui/)

Review URL: https://codereview.chromium.org/47923018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233977 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/extensions/extension_host.cc b/chrome/browser/extensions/extension_host.cc
index 4379dcb..a792eac 100644
--- a/chrome/browser/extensions/extension_host.cc
+++ b/chrome/browser/extensions/extension_host.cc
@@ -39,7 +39,6 @@
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/extension_messages.h"
-#include "chrome/common/extensions/feature_switch.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/content_browser_client.h"
@@ -54,6 +53,7 @@
 #include "extensions/browser/extension_error.h"
 #include "extensions/browser/view_type_utils.h"
 #include "extensions/common/extension_urls.h"
+#include "extensions/common/feature_switch.h"
 #include "grit/browser_resources.h"
 #include "grit/chromium_strings.h"
 #include "grit/generated_resources.h"