Update the child process security policy to use explicit permission grants.

content/public/browser/render_view_host.h

Index: content/public/browser/render_view_host.h
diff --git a/content/public/browser/render_view_host.h b/content/public/browser/render_view_host.h
index 20032c1a03be8c991ce5b24ffefbfddd3cc78552..bf5a9be4182f86dff8af949f99bcd0dd67c0d144 100644
--- a/content/public/browser/render_view_host.h
+++ b/content/public/browser/render_view_host.h
@@ -209,13 +209,17 @@ class CONTENT_EXPORT RenderViewHost : virtual public RenderWidgetHost {
   // closing the entire tab.
   virtual void FirePageBeforeUnload(bool for_cross_site_transition) = 0;
 
+  enum FileSelectionPermissions {
+    FILE_PERMISSION_READ_ONLY,
+    FILE_PERMISSION_WRITE
+  };
+
   // Notifies the Listener that one or more files have been chosen by the user
-  // from a file chooser dialog for the form. |permissions| are flags from the
-  // base::PlatformFileFlags enum which specify which file permissions should
-  // be granted to the renderer.
+  // from a file chooser dialog for the form. |permissions| is the permission
+  // security policy for the selected file.
   virtual void FilesSelectedInChooser(
       const std::vector<ui::SelectedFileInfo>& files,
-      int permissions) = 0;
+      FileSelectionPermissions permissions) = 0;
 
   virtual RenderViewHostDelegate* GetDelegate() const = 0;