[Telemetry] Move WPR life cycle from browser to platform

tools/telemetry/telemetry/core/network_controller.py

Index: tools/telemetry/telemetry/core/network_controller.py
diff --git a/tools/telemetry/telemetry/core/network_controller.py b/tools/telemetry/telemetry/core/network_controller.py
index 3df2e92f7e304451ae09047afa971ea7d8e328b5..116f67459fe7f76b99aed3d1be465c220d9bb19f 100644
--- a/tools/telemetry/telemetry/core/network_controller.py
+++ b/tools/telemetry/telemetry/core/network_controller.py
@@ -13,21 +13,46 @@ class NetworkController(object):
   def __init__(self, network_controller_backend):
     self._network_controller_backend = network_controller_backend
 
-  def SetReplayArgs(self,
-                    archive_path,
-                    wpr_mode,
-                    netsim,
-                    extra_wpr_args,
-                    make_javascript_deterministic=False):
-    """Save the arguments needed for replay."""
-    self._network_controller_backend.SetReplayArgs(
-        archive_path, wpr_mode, netsim, extra_wpr_args,
-        make_javascript_deterministic)
-
-  def UpdateReplayForExistingBrowser(self):
-    """Restart replay if needed for an existing browser.
-
-    TODO(slamm): Drop this method when the browser_backend dependencies are
-    moved to the platform. https://crbug.com/423962
+  def Open(self, wpr_mode, netsim=None, extra_wpr_args=None):
+    """Configure and start any changes needed for network control.
+
+    This may, as needed, install certificates or start port forwarding for
+    remote platforms. After network interactions are over, clients are expected
+    to call the Close method.
+
+    Args:
+      wpr_mode: a mode for web page replay; available options are
+          wpr_modes.WPR_OFF, wpr_modes.APPEND, wpr_modes.WPR_REPLAY, or
+          wpr_modes.WPR_RECORD.
+      netsim: an optional net_config string (e.g. 'dialup', '3g', 'dsl',
+          'cable', 'fios').
+      extra_wpr_args: an optional sequence of extra arguments for web page
+          replay.
+    """
+    self._network_controller_backend.Open(wpr_mode, netsim, extra_wpr_args)
+
+  def StartReplay(self, archive_path, make_javascript_deterministic=False):
+    """Start (or reuse) a replay server from a specific archive.
+
+    It will implicitly stop a previous replay if the archive_path or JavaScript
+    options differ.
+
+    Args:
+      archive_path: a path to a specific WPR archive.
+      make_javascript_deterministic: True if replay should inject a script
+          to make JavaScript behanve deterministically (e.g., override Date()).
+    """
+    self._network_controller_backend.StartReplay(
+        archive_path, make_javascript_deterministic)
+
+  def StopReplay(self):
+    """Close the currently active replay server, if any."""
+    self._network_controller_backend.StopReplay()
+
+  def Close(self):
+    """Undo any changes that were applied for network control.
+
+    This also stops any port forwarders and implicitly calls StopReplay
+    if needed.
     """
-    self._network_controller_backend.UpdateReplay()
+    self._network_controller_backend.Close()