Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/profiles/profile.h

Index: chrome/browser/profiles/profile.h
diff --git a/chrome/browser/profiles/profile.h b/chrome/browser/profiles/profile.h
index b78b8bb9c242be3337233c923543893c06b18ff1..c3b2983c6e4e979a387010f81249de39819bef9d 100644
--- a/chrome/browser/profiles/profile.h
+++ b/chrome/browser/profiles/profile.h
@@ -36,6 +36,10 @@ class SequencedTaskRunner;
 class Time;
 }
 
+namespace chrome {
+class ChromeZoomLevelPrefs;
+}
+
 namespace chrome_browser_net {
 class Predictor;
 }
@@ -220,6 +224,11 @@ class Profile : public content::BrowserContext {
   // preferences for this user profile.
   virtual PrefService* GetPrefs() = 0;
 
+  // Retrieves a pointer to the PrefService that manages the default zoom
+  // level and the per-host zoom levels for this user profile.
+  // TODO(wjmaclean): Remove this when HostZoomMap migrates to StoragePartition.
+  virtual chrome::ChromeZoomLevelPrefs* GetZoomLevelPrefs();
+
   // Retrieves a pointer to the PrefService that manages the preferences
   // for OffTheRecord Profiles.  This PrefService is lazily created the first
   // time that this method is called.