[Telemetry] Move WPR life cycle from browser to platform

tools/telemetry/telemetry/internal/platform/android_platform_backend.py

Index: tools/telemetry/telemetry/internal/platform/android_platform_backend.py
diff --git a/tools/telemetry/telemetry/internal/platform/android_platform_backend.py b/tools/telemetry/telemetry/internal/platform/android_platform_backend.py
index 86264d887713967afa7e15fc42cf3fa98f23ecda..77547e63ccc5a40d24b5d7c8ccac8d763cb4b138 100644
--- a/tools/telemetry/telemetry/internal/platform/android_platform_backend.py
+++ b/tools/telemetry/telemetry/internal/platform/android_platform_backend.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import logging
+import numbers
 import os
 import re
 import shutil
@@ -501,7 +502,47 @@ class AndroidPlatformBackend(
     return old_flag
 
   def ForwardHostToDevice(self, host_port, device_port):
-    self._device.adb.Forward('tcp:%d' % host_port, device_port)
+    """Forward host to device using adb.
+
+    Also prints lots of useful debug information in case of failure.
+
+    Args:
+      host_port, device_port: The host and device ports to pair. Each may be
+          given as an integer (assumed to be a tcp port), or a string with
+          a named socket.
+    """
+    if isinstance(host_port, numbers.Integral):
+      host_port = 'tcp:%d' % host_port
+    if isinstance(device_port, numbers.Integral):
+      device_port = 'tcp:%d' % device_port
+    try:
+      self._device.adb.Forward(host_port, device_port)
+      logging.info('Forwarding host %s to device %s.', host_port, device_port)
+    except Exception:
+      logging.exception('Failed to forward %s to %s.', host_port, device_port)
+      logging.warning('Currently forwarding:')
+      try:
+        for line in self._device.adb.ForwardList().splitlines():
+          logging.warning('  %s', line)
+      except Exception:
+        logging.warning('Exception raised while listing forwarded connections.')
+
+      logging.warning('Host tcp ports in use:')
+      try:
+        for line in subprocess.check_output(['netstat', '-t']).splitlines():
+          logging.warning('  %s', line)
+      except Exception:
+        logging.warning('Exception raised while listing tcp ports.')
+
+      logging.warning('Device unix domain sockets in use:')
+      try:
+        for line in self._device.ReadFile('/proc/net/unix', as_root=True,
+                                          force_pull=True).splitlines():
+          logging.warning('  %s', line)
+      except Exception:
+        logging.warning('Exception raised while listing unix domain sockets.')
+
+      raise  # Re-raise the exception.
 
   def StopForwardingHost(self, host_port):
     for line in self._device.adb.ForwardList().strip().splitlines():