Telemetry: Move Web Page Replay to the platform.

tools/telemetry/telemetry/core/platform/network_controller_backend.py

Index: tools/telemetry/telemetry/core/platform/network_controller_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/network_controller_backend.py b/tools/telemetry/telemetry/core/platform/network_controller_backend.py
new file mode 100644
index 0000000000000000000000000000000000000000..d77ea0343adf7c62d516c5a9bc50e5171495f274
--- /dev/null
+++ b/tools/telemetry/telemetry/core/platform/network_controller_backend.py
@@ -0,0 +1,107 @@
+# Copyright 2014 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.
+
+import os
+
+from telemetry.core import wpr_modes
+from telemetry.core import wpr_server
+
+
+class ArchiveDoesNotExistError(Exception):
+  """Raised when the archive path does not exist for replay mode."""
+  pass
+
+
+class ReplayAndBrowserPortsError(Exception):
+  """Raised an existing browser would get different remote replay ports."""
+  pass
+
+
+class NetworkControllerBackend(object):
+  """Control network settings and servers to simulate the Web.
+
+  Network changes include forwarding device ports to host platform ports.
+  Web Page Replay is used to record and replay HTTP/HTTPS responses.
+  """
+
+  def __init__(self, platform_backend):
+    self._platform_backend = platform_backend
+    self._browser_backend = None
+    self._wpr_server = None
+    self._active_replay_args = {}
+    self._pending_replay_args = {}
+
+  def SetReplayArgs(self, archive_path, wpr_mode, netsim, extra_wpr_args,
+                    make_javascript_deterministic=False):
+    """Save the arguments needed for replay.
+
+    To make the settings effective, this call must be followed by a call
+    to UpdateReplay.
+
+    Args:
+      archive_path: a path to a specific WPR archive.
+      wpr_mode: one of wpr_modes.WPR_OFF, wpr_modes.WPR_APPEND,
+          wpr_modes.WPR_REPLAY, or wpr_modes.WPR_RECORD.
+      netsim: a net_config string ('dialup', '3g', 'dsl', 'cable', or 'fios').
+      extra_wpr_args: a list of addtional replay args (or an empty list).
+      make_javascript_deterministic: True if replay should inject a script
+          to make JavaScript behave deterministically (e.g., override Date()).
+    """
+    self._pending_replay_args = dict(
+        archive_path=archive_path,
+        wpr_mode=wpr_mode,
+        netsim=netsim,
+        extra_wpr_args=extra_wpr_args,
+        make_javascript_deterministic=make_javascript_deterministic)
+    # TODO(slamm): Update replay here when the browser_backend dependencies
+    # are moved to the platform. https://crbug.com/423962
+    # |self._pending_replay_args| can be removed at that time.
+
+  def UpdateReplay(self, browser_backend=None):
+    """Start or reuse Web Page Replay.
+
+    UpdateReplay must be called after every call to SetReplayArgs.
+
+    TODO(slamm): Update replay in SetReplayArgs once the browser_backend
+        dependencies move to platform. https://crbug.com/423962
+        browser_backend properties used:
+          - Input: forwarder_factory, wpr_port_pairs, wpr_ca_cert_path
+          - Output: wpr_port_pairs (browser uses for --testing-fixed-* flags).
+    Args:
+      browser_backend: instance of telemetry.core.backends.browser_backend
+    """
+    if not self._pending_replay_args:
+      # In some cases (e.g., unit tests), the browser is used without replay.
+      return
+    if self._pending_replay_args == self._active_replay_args:
+      return
+
+    self.StopReplay()
+
+    pending_archive_path = self._pending_replay_args['archive_path']
+    pending_wpr_mode = self._pending_replay_args['wpr_mode']
+    if not pending_archive_path or pending_wpr_mode == wpr_modes.WPR_OFF:
+      return
+    if (pending_wpr_mode == wpr_modes.WPR_REPLAY and
+        not os.path.exists(pending_archive_path)):
+      raise ArchiveDoesNotExistError(
+          'Archive path does not exist: %s' % pending_archive_path)
+    if browser_backend:
+      self._browser_backend = browser_backend
+    else:
+      # If no browser_backend, then this is an update for an existing wpr.
+      assert self._browser_backend
+    self._wpr_server = self._ReplayServer(
+        self._browser_backend, self._pending_replay_args)
+    self._active_replay_args = self._pending_replay_args
+    self._pending_replay_args = None
+
+  def _ReplayServer(self, browser_backend, replay_args):
+    return wpr_server.ReplayServer(browser_backend, **replay_args)
+
+  def StopReplay(self):
+    if self._wpr_server:
+      self._wpr_server.Close()
+      self._wpr_server = None
+      self._active_replay_args = {}