[Clean up] Remove code related to install test ca in Telemetry

telemetry/telemetry/internal/platform/platform_backend.py

Index: telemetry/telemetry/internal/platform/platform_backend.py
diff --git a/telemetry/telemetry/internal/platform/platform_backend.py b/telemetry/telemetry/internal/platform/platform_backend.py
index ecf4d3f523ccd4604ffb7b0c653ad03006e62703..20ea1a21f2b41374406deb27ea0546f7f0e74ba3 100644
--- a/telemetry/telemetry/internal/platform/platform_backend.py
+++ b/telemetry/telemetry/internal/platform/platform_backend.py
@@ -266,19 +266,6 @@ class PlatformBackend(object):
     """
     raise NotImplementedError()
 
-  @property
-  def supports_test_ca(self):
-    """Indicates whether the platform supports installing test CA."""
-    return False
-
-  def InstallTestCa(self):
-    """Install a test CA on the platform."""
-    raise NotImplementedError()
-
-  def RemoveTestCa(self):
-    """Remove a previously installed test CA from the platform."""
-    raise NotImplementedError()
-
   def CanTakeScreenshot(self):
     return False