Remove the id field of inspector_backend since no public caller uses it

tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py b/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
index bd7680c073da3163389ecb311ae6b015ebe2c0e8..642257161125c80e6ff3de701ed97ef00f8072fa 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/inspector_backend.py
@@ -74,15 +74,11 @@ class InspectorBackend(inspector_websocket.InspectorWebsocket):
   @property
   def url(self):
     for c in self._browser_backend.ListInspectableContexts():
-      if c['id'] == self.id:
+      if c['id'] == self._context['id']:
         return c['url']
     return None
 
   @property
-  def id(self):
-    return self._context['id']
-
-  @property
   def debugger_url(self):
     return self._context['webSocketDebuggerUrl']