Remove unused HeuristicLanguageModel code

This change also deprecates the kUserLanguageProfile pref.

Change-Id: I7583c22d1e77c1d2af55476923efe12ab4cdfe6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3057021
Reviewed-by: Mike Dougherty <[email protected]>
Reviewed-by: Megan Jablonski <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Commit-Queue: Anthony Cui <[email protected]>
Cr-Commit-Position: refs/heads/master@{#906949}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 2061617..adff84d 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -644,6 +644,9 @@
 // Deprecated 07/2021.
 const char kAccountStorageExists[] = "profile.password_account_storage_exists";
 
+// Deprecated 07/2021.
+const char kUserLanguageProfile[] = "language_profile";
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -831,6 +834,8 @@
 #endif
 
   registry->RegisterBooleanPref(kAccountStorageExists, false);
+
+  registry->RegisterDictionaryPref(kUserLanguageProfile);
 }
 
 }  // namespace
@@ -1628,6 +1633,9 @@
   // Added 2021/07.
   profile_prefs->ClearPref(kAccountStorageExists);
 
+  // Added 07/2021
+  profile_prefs->ClearPref(kUserLanguageProfile);
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_PROFILE_PREFS
 }