measuring the time it takes to render a tile

Change-Id: I37db170af0e507c99d571b94ff78a1987944290e

ios/shared/ios_sharedlo/objective_c/view_controllers/testing_tiles/MLOTestingTile.m

@@ -43,6 +43,7 @@
 
 - (void)drawRect:(CGRect)rect
 {
+    NSTimeInterval startTime = CACurrentMediaTime();
     CGContextRef context = UIGraphicsGetCurrentContext();
 
     MLODpxPoint tilePosition =MLODpxPointByDpxes(self.tester.params.tilePosX,self.tester.params.tilePosY);
@@ -62,6 +63,7 @@
                        tilePosition,
                        tileSize);
 
+    NSLog(@"tile rendering took %f seconds",CACurrentMediaTime() - startTime);
     MLODpxSize size = touch_lo_get_content_size();
     NSLog(@"touch_lo_get_content_size: width=%f, height=%f",size.width, size.height);
 }