Rewrite std::string("") to std::string(), Linux edition.

ppapi/native_client/src/trusted/plugin/plugin.cc

Index: ppapi/native_client/src/trusted/plugin/plugin.cc
diff --git a/ppapi/native_client/src/trusted/plugin/plugin.cc b/ppapi/native_client/src/trusted/plugin/plugin.cc
index e1f3ad939c7023e3cd91f7c50f441317af9d51cc..7b2f0a9e9ef58658bba208a6ff49a12c50412cd4 100644
--- a/ppapi/native_client/src/trusted/plugin/plugin.cc
+++ b/ppapi/native_client/src/trusted/plugin/plugin.cc
@@ -677,7 +677,6 @@ bool Plugin::Init(uint32_t argc, const char* argn[], const char* argv[]) {
   return status;
 }
 
-
 Plugin::Plugin(PP_Instance pp_instance)
     : pp::InstancePrivate(pp_instance),
       scriptable_plugin_(NULL),
@@ -688,7 +687,6 @@ Plugin::Plugin(PP_Instance pp_instance)
       nacl_ready_state_(UNSENT),
       nexe_error_reported_(false),
       wrapper_factory_(NULL),
-      last_error_string_(""),
       enable_dev_interfaces_(false),
       is_installed_(false),
       init_time_(0),