ews: replace open-coded time unit conversion in request logging

Defer calling .count() until it is actually needed at the printf site
to increase type safety involving the age() function.

exch/ews/context.cpp

@@ -342,11 +342,6 @@ EWSContext::~EWSContext()
 			unsubscribe(sub);
 }
 
-double EWSContext::age() const
-{
-	return std::chrono::duration<double>(tp_now() - m_created).count();
-}
-
 /**
  * @brief      Copy string to context allocated buffer
  *

exch/ews/ews.cpp

@@ -736,7 +736,7 @@ int EWSPlugin::retr(int ctx_id) try
 			mlog(loglevel, "[ews#%d]%s Done, code %d, %zu bytes, %.3fms",
 				ctx_id, timestamp().c_str(),
 				static_cast<int>(context.code()),
-				sv.size(), context.age() * 1000);
+				sv.size(), std::chrono::duration<double, std::milli>(context.age()).count());
 		return HPM_RETRIEVE_WRITE;
 	}
 	case EWSContext::S_DONE: return HPM_RETRIEVE_DONE;

exch/ews/ews.hpp

@@ -304,7 +304,7 @@ class EWSContext {
 	void validate(const std::string&, const Structures::sMessageEntryId&) const;
 	void writePermissions(const std::string&, uint64_t, const std::vector<PERMISSION_DATA>&) const;
 
-	double age() const;
+	gromox::time_duration age() const { return tp_now() - m_created; }
 	void experimental(const char*) const;
 
 	inline int ID() const {return m_ID;}