Replace --ppapi-keep-alive-throttle command line switch with IPC parameter.

components/nacl/browser/nacl_process_host.h

Index: components/nacl/browser/nacl_process_host.h
diff --git a/components/nacl/browser/nacl_process_host.h b/components/nacl/browser/nacl_process_host.h
index 9df7ade359b44d4cb6ba65af81fef9c4785b6025..eab94cde6b447172149eb1b43198597304417f2d 100644
--- a/components/nacl/browser/nacl_process_host.h
+++ b/components/nacl/browser/nacl_process_host.h
@@ -78,6 +78,9 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
   // Do any minimal work that must be done at browser startup.
   static void EarlyStartup();
 
+  // Specifies throttling time in milliseconds for PpapiHostMsg_Keepalive IPCs.
+  static void SetPpapiKeepAliveThrottleForTesting(unsigned milliseconds);
+
   // Initialize the new NaCl process. Result is returned by sending ipc
   // message reply_msg.
   void Launch(NaClHostMessageFilter* nacl_host_message_filter,
@@ -220,6 +223,9 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
 
   int render_view_id_;
 
+  // Throttling time in milliseconds for PpapiHostMsg_Keepalive IPCs.
+  static unsigned keepalive_throttle_interval_milliseconds_;
+
   DISALLOW_COPY_AND_ASSIGN(NaClProcessHost);
 };