RN: Change Time Drift Error into Warning

Summary: Changes the time drift error into a warning that will only get logged once per debugging session.

Reviewed By: jingc

Differential Revision: D3539067

fbshipit-source-id: 357db15750d867a91c39b5fc5fd6ed4ae2852bc7

Libraries/JavaScriptAppEngine/System/JSTimers/JSTimersExecution.js

@@ -16,6 +16,8 @@ var performanceNow = require('fbjs/lib/performanceNow');
 var warning = require('fbjs/lib/warning');
 var Systrace = require('Systrace');
 
+let hasEmittedTimeDriftWarning = false;
+
 /**
  * JS implementation of timer functions. Must be completely driven by an
  * external clock signal, all that's stored here is timerID, timer type, and
@@ -147,6 +149,17 @@ var JSTimersExecution = {
     }
   },
 
+  /**
+   * Called from native (in development) when environment times are out-of-sync.
+   */
+  emitTimeDriftWarning: function(warningMessage) {
+    if (hasEmittedTimeDriftWarning) {
+      return;
+    }
+    hasEmittedTimeDriftWarning = true;
+    console.warn(warningMessage);
+  },
+
   _clearIndex: function(i) {
     JSTimersExecution.timerIDs[i] = null;
     JSTimersExecution.callbacks[i] = null;