Migrate HostZoomMap to live in StoragePartition.

content/public/browser/browser_context.h

Index: content/public/browser/browser_context.h
diff --git a/content/public/browser/browser_context.h b/content/public/browser/browser_context.h
index fec68dc320f51bc4e835923ffd565fca847419c1..02b83e79d13a3665b08fad6aa437555cdfb3ceff 100644
--- a/content/public/browser/browser_context.h
+++ b/content/public/browser/browser_context.h
@@ -10,6 +10,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/supports_user_data.h"
 #include "content/common/content_export.h"
+#include "content/public/browser/zoom_level_delegate.h"
 #include "content/public/common/push_messaging_status.h"
 
 class GURL;
@@ -111,6 +112,11 @@ class CONTENT_EXPORT BrowserContext : public base::SupportsUserData {
 
   ~BrowserContext() override;
 
+  // Creates a delegate to initialize a HostZoomMap and persist its information.
+  // This is called during creation of each StoragePartition.
+  virtual scoped_ptr<ZoomLevelDelegate> CreateZoomLevelDelegate(
+      const base::FilePath& partition_path) = 0;
+
   // Returns the path of the directory where this context's data is stored.
   virtual base::FilePath GetPath() const = 0;