Add support for signing HTTPS with self-signed root certificate.

tools/telemetry/telemetry/core/backends/browser_backend.py

Index: tools/telemetry/telemetry/core/backends/browser_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/browser_backend.py b/tools/telemetry/telemetry/core/backends/browser_backend.py
index 26b5df4cf04e69a9c680b1e81eec8acce7ba9f37..283827b41bf8e1fb2698aac41241f7f01f2d18e1 100644
--- a/tools/telemetry/telemetry/core/backends/browser_backend.py
+++ b/tools/telemetry/telemetry/core/backends/browser_backend.py
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import os
+
 from telemetry import decorators
 from telemetry.core import platform
 from telemetry.core import web_contents
@@ -23,6 +25,7 @@ class BrowserBackend(object):
     self._browser = None
     self._tab_list_backend_class = tab_list_backend
     self._forwarder_factory = None
+    self._wpr_ca_cert_path = None
 
   def AddReplayServerOptions(self, extra_wpr_args):
     pass
@@ -48,6 +51,16 @@ class BrowserBackend(object):
     return self.browser_options.wpr_mode
 
   @property
+  def wpr_ca_cert_path(self):
+    """Path to root certificate installed on browser (or None).
+
+    If this is set, web page replay will use it to sign HTTPS responses.
+    """
+    if self._wpr_ca_cert_path:
+      assert os.path.isfile(self._wpr_ca_cert_path)
+    return self._wpr_ca_cert_path
+
+  @property
   def supports_tab_control(self):
     raise NotImplementedError()