Remove profile-based per-host & default zoom level migration code.

chrome/browser/prefs/browser_prefs.h

Index: chrome/browser/prefs/browser_prefs.h
diff --git a/chrome/browser/prefs/browser_prefs.h b/chrome/browser/prefs/browser_prefs.h
index 122ebe4920e775c82ad6b55816397e70dbc4f122..2d69a7d4fe8275245d53d0490fff6081b80f6b29 100644
--- a/chrome/browser/prefs/browser_prefs.h
+++ b/chrome/browser/prefs/browser_prefs.h
@@ -42,10 +42,6 @@ void MigrateObsoleteBrowserPrefs(Profile* profile, PrefService* local_state);
 // should remain *the* place to drop deprecated profile prefs at.
 void MigrateObsoleteProfilePrefs(Profile* profile);
 
-// Migrates zoom level prefs in |profile|'s pref store to a per-StoragePartition
-// set of prefs.
-void MigrateProfileZoomLevelPrefs(Profile* profile);
-
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_PREFS_BROWSER_PREFS_H_