[signin] Add feature flag for mobile account consistency on Android

The CL adds the flag and plumbs it to the reconcilor.

A basic version of the Mice reconcilor is created. It is not functional
yet, but will be improved in future CLs.

Change-Id: I0df18ba41690db6c87d59ebcfa7f84a65bbbb7bc
Reviewed-on: https://chromium-review.googlesource.com/c/1475533
Reviewed-by: Elly Fong-Jones <[email protected]>
Reviewed-by: Boris Sazonov <[email protected]>
Commit-Queue: David Roger <[email protected]>
Cr-Commit-Position: refs/heads/master@{#634177}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index fa67be0d..4e32335 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -750,6 +750,9 @@
 extern const char kMessageCenterNewStyleNotificationName[];
 extern const char kMessageCenterNewStyleNotificationDescription[];
 
+extern const char kMobileIdentityConsistencyName[];
+extern const char kMobileIdentityConsistencyDescription[];
+
 extern const char kNewAudioRenderingMixingStrategyName[];
 extern const char kNewAudioRenderingMixingStrategyDescription[];