Move language detection to chrome/common/.

This CL moves the language detection code from chrome/renderer/translate
to chrome/common/translate, in order to be able to use it on iOS.
This CL also enables the related unittests on iOS.

BUG=

Review URL: https://chromiumcodereview.appspot.com/18911002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@211108 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -538,7 +538,7 @@
           'enable_automation%': 0,
           'enable_extensions%': 0,
           'enable_google_now%': 0,
-          'enable_language_detection%': 0,
+          'enable_language_detection%': 1,
           'enable_printing%': 0,
           'enable_session_service%': 0,
           'enable_themes%': 0,