Upgrade loading_model to use the new request_track and loading_trace.

tools/android/loading/request_track_unittest.py

Index: tools/android/loading/request_track_unittest.py
diff --git a/tools/android/loading/request_track_unittest.py b/tools/android/loading/request_track_unittest.py
index ac08b30504e3265c1cc577bae20f2b06f444554f..97ea57fd32e6db3258ba077d8e4f96ef6973b70d 100644
--- a/tools/android/loading/request_track_unittest.py
+++ b/tools/android/loading/request_track_unittest.py
@@ -268,6 +268,21 @@ class RequestTrackTestCase(unittest.TestCase):
     request_track = RequestTrack.FromJsonDict(json_dict)
     self.assertEquals(self.request_track, request_track)
 
+  def testMaxAge(self):
+    rq = Request()
+    self.assertEqual(-1, rq.MaxAge())
+    rq.response_headers = {}
+    self.assertEqual(-1, rq.MaxAge())
+    rq.response_headers[
+        'Cache-Control'] = 'private,s-maxage=0,max-age=0,must-revalidate'
+    self.assertEqual(0, rq.MaxAge())
+    rq.response_headers[
+        'Cache-Control'] = 'private,s-maxage=0,no-store,max-age=100'
+    self.assertEqual(-1, rq.MaxAge())
+    rq.response_headers[
+        'Cache-Control'] = 'private,s-maxage=0'
+    self.assertEqual(-1, rq.MaxAge())
+
   @classmethod
   def _ValidSequence(cls, request_track):
     request_track.Handle(