[telemetry] Removing flake in wpr_server.py caused by static port assignment from chrome/test/funct…

tools/telemetry/telemetry/cros_browser_backend.py

Index: tools/telemetry/telemetry/cros_browser_backend.py
diff --git a/tools/telemetry/telemetry/cros_browser_backend.py b/tools/telemetry/telemetry/cros_browser_backend.py
index c66c88e5c48a5d493d1d67f79e459033317ae8e4..bcc41cfe0b76f2cb15431f2601ac95d6af05613e 100644
--- a/tools/telemetry/telemetry/cros_browser_backend.py
+++ b/tools/telemetry/telemetry/cros_browser_backend.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 import logging
 import os
+import re
 import socket
 import subprocess
 
@@ -24,6 +25,10 @@ class CrOSBrowserBackend(browser_backend.BrowserBackend):
     # Ensure the UI is running and logged out.
     self._RestartUI()
 
+    # http/https ports for remote chrome instance.
+    self.http_port = None
+    self.https_port = None
+
     # Delete test@test.test's cryptohome vault (user data directory).
     if not options.dont_override_profile:
       logging.info('Deleting user\'s cryptohome vault (the user data dir)')
@@ -77,6 +82,15 @@ class CrOSBrowserBackend(browser_backend.BrowserBackend):
   def GetBrowserStartupArgs(self):
     args = super(CrOSBrowserBackend, self).GetBrowserStartupArgs()
 
+    self.http_port = self._cri.GetRemotePort()
+    self.https_port = self._cri.GetRemotePort()
+
+    for x in range(len(args)):
+      args[x] = re.sub(r'(http-port=)\d*', r'\g<1>%i' % self.http_port, args[x])
+      args[x] = re.sub(r'(https-port=)\d*', r'\g<1>%i' % self.https_port,
+                       args[x])
+
+
     args.extend([
             '--allow-webui-compositing',
             '--aura-host-window-use-fullscreen',
@@ -130,15 +144,18 @@ class CrOSBrowserBackend(browser_backend.BrowserBackend):
 class SSHForwarder(object):
   def __init__(self, cri, forwarding_flag, *ports):
     self._proc = None
-    self._host_port = ports[0][0]
-
     port_pairs = []
 
     for port in ports:
-      if port[1] is None:
-        port_pairs.append((port[0], cri.GetRemotePort()))
-      else:
-        port_pairs.append(port)
+      port1 = port[0]
+      port2 = port[1]
+      if port1 is None:
+        port1 = cri.GetRemotePort()
+      if port2 is None:
+        port2 = cri.GetRemotePort()
+      port_pairs.append((port1, port2))
+
+    self._host_port = port_pairs[0][0]
 
     if forwarding_flag == 'R':
       self._device_port = port_pairs[0][0]