tools/android/loading: Properly detect page loading failures

tools/android/loading/tracing.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Monitor tracing events on chrome via chrome remote debugging."""
 
 import itertools
 import logging
 import operator
 
@@ skipping 68 matching lines @@
 
   def GetMatchingMainFrameEvents(self, category, name):
     """Gets events matching |category| and |name| that occur in the main frame.
 
     Events without a 'frame' key in their |args| are discarded.
     """
     matching_events = self.GetMatchingEvents(category, name)
     return [e for e in matching_events
         if 'frame' in e.args and e.args['frame'] == self.GetMainFrameID()]
 
+  def GetMainFrameRoutingID(self):
+    """Returns the main frame routing ID."""
+    for event in self.GetMatchingEvents(
+        'navigation', 'RenderFrameImpl::OnNavigate'):
+      return event.args['id']
+    assert False
+
   def GetMainFrameID(self):
     """Returns the main frame ID."""
     if not self._main_frame_id:
       navigation_start_events = self.GetMatchingEvents(
           'blink.user_timing', 'navigationStart')
       first_event = min(navigation_start_events, key=lambda e: e.start_msec)
       self._main_frame_id = first_event.args['frame']
 
     return self._main_frame_id
 
@@ skipping 443 matching lines @@
     self._left = _IntervalTree(self.start, left_end, left_events)
     self._right = _IntervalTree(right_start, self.end, right_events)
 
   def _IsLeaf(self):
     return self._left is None
 
   @classmethod
   def _Overlaps(cls, event, start, end):
     return (min(end, event.end_msec) - max(start, event.start_msec) > 0
             or start <= event.start_msec < end)  # For instant events.