Keep NaCl plugins used in app background pages alive when active.

components/nacl/browser/nacl_browser_delegate.h

Index: components/nacl/browser/nacl_browser_delegate.h
diff --git a/components/nacl/browser/nacl_browser_delegate.h b/components/nacl/browser/nacl_browser_delegate.h
index 0540f60d10997a8f24cf23eb419e60094987272f..30bf467581a52fd1262895561ec2f53c7422ced4 100644
--- a/components/nacl/browser/nacl_browser_delegate.h
+++ b/components/nacl/browser/nacl_browser_delegate.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/callback_forward.h"
+#include "content/public/browser/browser_ppapi_host.h"
 
 class GURL;
 
@@ -21,10 +22,6 @@ class HostFactory;
 }
 }
 
-namespace content {
-class BrowserPpapiHost;
-}
-
 // Encapsulates the dependencies of NaCl code on chrome/, to avoid a direct
 // dependency on chrome/.
 class NaClBrowserDelegate {
@@ -73,6 +70,10 @@ class NaClBrowserDelegate {
 
   // Returns whether NaCl application with this manifest URL should be debugged.
   virtual bool URLMatchesDebugPatterns(const GURL& manifest_url) = 0;
+
+  // Returns a callback that handles NaCl idle state transitions.
+  virtual content::BrowserPpapiHost::OnKeepaliveCallback
+      GetOnKeepaliveCallback() = 0;
 };
 
 #endif  // COMPONENTS_NACL_BROWSER_NACL_BROWSER_DELEGATE_H_