sandwich: Implements network condition on WPR server and browser.

tools/android/loading/devtools_monitor.py

Index: tools/android/loading/devtools_monitor.py
diff --git a/tools/android/loading/devtools_monitor.py b/tools/android/loading/devtools_monitor.py
index 5279e4f6d327a73e6de03d40d84a48088697f4f1..5e69d7a101b319ab4572b8eb3d5c3b7f1a9f33dc 100644
--- a/tools/android/loading/devtools_monitor.py
+++ b/tools/android/loading/devtools_monitor.py
@@ -20,6 +20,9 @@ from telemetry.internal.backends.chrome_inspector import inspector_websocket
 from telemetry.internal.backends.chrome_inspector import websocket
 
 
+DEFAULT_TIMEOUT = 10 # seconds
+
+
 class DevToolsConnectionException(Exception):
   def __init__(self, message):
     super(DevToolsConnectionException, self).__init__(message)
@@ -189,20 +192,21 @@ class DevToolsConnection(object):
     self._tearing_down_tracing = False
     self._set_up = True
 
-  def StartMonitoring(self):
+  def StartMonitoring(self, timeout=DEFAULT_TIMEOUT):
     """Starts monitoring.
 
     DevToolsConnection.SetUpMonitoring() has to be called first.
     """
     assert self._set_up, 'DevToolsConnection.SetUpMonitoring not called.'
-    self._Dispatch()
+    self._Dispatch(timeout=timeout)
     self._TearDownMonitoring()
 
   def StopMonitoring(self):
     """Stops the monitoring."""
     self._please_stop = True
 
-  def _Dispatch(self, kind='Monitoring', timeout=10):
+  def _Dispatch(self, kind='Monitoring',
+                timeout=DEFAULT_TIMEOUT):

[mattcary, 2016/02/19 15:40:17]

this timeout should be configured as part of the devtools connection. It gets
very unmaintainable passing all these configuration details as method
parameters.

[gabadie, 2016/02/22 10:05:00]

Agreed. But to me only few dispatch calls needed a longer timeout. Since this
custom timeout is significantly higher, it was making sens to not apply it to
every call and have a per call granularity.

To solve the maintainability, the TraceRecorder proposal was my solution,
because he could take car e of this. "Oh you are running on android with a 2g
emulated network on the browser side, let me change this timeout silently for
you so that you don't have to deal with it in your upper layers".

     self._please_stop = False
     while not self._please_stop:
       try: