Fix upload remaining time

The upload remaining time is always 'a few second' whatever a big or a
small file uploading.
This commit fixes it. The `new Date().getMilliseconds()` only return a
three digits number. When time arrived the next second, the millisecond
start from ZERO again. So `new Date().getTime()` is the righe choice.
And remaining time variables shoule be initialized when the file starts
uploading, otherwise the remaining time of a new upload will always be
'Infinity years' until you refresh the page.

Signed-off-by: Yaojin Qian <i@ume.ink>

apps/files/js/file-upload.js

@@ -956,16 +956,7 @@ OC.Uploader.prototype = _.extend({
 
 			if (this._supportAjaxUploadWithProgress()) {
 				//remaining time
-				var lastUpdate = new Date().getMilliseconds();
-				var lastSize = 0;
-				var bufferSize = 20;
-				var buffer = [];
-				var bufferIndex = 0;
-				var bufferIndex2 = 0;
-				var bufferTotal = 0;
-				for(var i = 0; i < bufferSize;i++){
-					buffer[i] = 0;
-				}
+				var lastUpdate, lastSize, bufferSize, buffer, bufferIndex, bufferIndex2, bufferTotal;
 
 				// add progress handlers
 				fileupload.on('fileuploadadd', function(e, data) {
@@ -986,6 +977,17 @@ OC.Uploader.prototype = _.extend({
 							+ '</span></em>');
 					$('#uploadprogressbar').tooltip({placement: 'bottom'});
 					self._showProgressBar();
+					// initial remaining time variables
+					lastUpdate   = new Date().getTime();
+					lastSize     = 0;
+					bufferSize   = 20;
+					buffer       = [];
+					bufferIndex  = 0;
+					bufferIndex2 = 0;
+					bufferTotal  = 0;
+					for(var i = 0; i < bufferSize; i++){
+						buffer[i]  = 0;
+					}
 					self.trigger('start', e, data);
 				});
 				fileupload.on('fileuploadprogress', function(e, data) {
@@ -996,12 +998,12 @@ OC.Uploader.prototype = _.extend({
 				fileupload.on('fileuploadprogressall', function(e, data) {
 					self.log('progress handle fileuploadprogressall', e, data);
 					var progress = (data.loaded / data.total) * 100;
-					var thisUpdate = new Date().getMilliseconds();
+					var thisUpdate = new Date().getTime();
 					var diffUpdate = (thisUpdate - lastUpdate)/1000; // eg. 2s
 					lastUpdate = thisUpdate;
 					var diffSize = data.loaded - lastSize;
 					lastSize = data.loaded;
-					diffSize = diffSize / diffUpdate; // apply timing factor, eg. 1mb/2s = 0.5mb/s
+					diffSize = diffSize / diffUpdate; // apply timing factor, eg. 1MiB/2s = 0.5MiB/s, unit is byte per second
 					var remainingSeconds = ((data.total - data.loaded) / diffSize);
 					if(remainingSeconds >= 0) {
 						bufferTotal = bufferTotal - (buffer[bufferIndex]) + remainingSeconds;