Test Keeping NaCl plugins used in app background pages alive when active.

ppapi/proxy/plugin_main_nacl.cc

Index: ppapi/proxy/plugin_main_nacl.cc
diff --git a/ppapi/proxy/plugin_main_nacl.cc b/ppapi/proxy/plugin_main_nacl.cc
index bced1083f0d53bcc310c187c24f5ed6d00702640..6690f2059cba8ee6f3e1dd6e73adf8ced9617b08 100644
--- a/ppapi/proxy/plugin_main_nacl.cc
+++ b/ppapi/proxy/plugin_main_nacl.cc
@@ -13,6 +13,7 @@
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "components/tracing/child_trace_message_filter.h"
@@ -29,6 +30,7 @@
 #include "ppapi/proxy/plugin_message_filter.h"
 #include "ppapi/proxy/plugin_proxy_delegate.h"
 #include "ppapi/proxy/resource_reply_thread_registrar.h"
+#include "ppapi/shared_impl/ppapi_switches.h"
 #include "ppapi/shared_impl/ppb_audio_shared.h"
 
 #if defined(IPC_MESSAGE_LOG_ENABLED)
@@ -95,6 +97,8 @@ class PpapiDispatcher : public ProxyChannel,
                               SerializedHandle handle);
   void OnPluginDispatcherMessageReceived(const IPC::Message& msg);
 
+  void SetPpapiKeepAliveThrottleFromCommandLine();
+
   std::set<PP_Instance> instances_;
   std::map<uint32, PluginDispatcher*> plugin_dispatchers_;
   uint32 next_plugin_dispatcher_id_;
@@ -208,6 +212,7 @@ void PpapiDispatcher::OnMsgCreateNaClChannel(
     logging::LoggingSettings settings;
     settings.logging_dest = logging::LOG_TO_SYSTEM_DEBUG_LOG;
     logging::InitLogging(settings);
+    SetPpapiKeepAliveThrottleFromCommandLine();
     command_line_and_logging_initialized = true;
   }
   // Tell the process-global GetInterface which interfaces it can return to the
@@ -250,6 +255,18 @@ void PpapiDispatcher::OnPluginDispatcherMessageReceived(
     dispatcher->second->OnMessageReceived(msg);
 }
 
+void PpapiDispatcher::SetPpapiKeepAliveThrottleFromCommandLine() {
+  unsigned keepalive_throttle_interval_milliseconds = 0;
+  if (base::StringToUint(
+          CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+              switches::kPpapiKeepAliveThrottle),
+          &keepalive_throttle_interval_milliseconds)) {
+    ppapi::proxy::PluginGlobals::Get()->
+        set_keepalive_throttle_interval_milliseconds(
+            keepalive_throttle_interval_milliseconds);
+  }
+}
+
 }  // namespace
 
 void PpapiPluginRegisterThreadCreator(