[WIP] DevToolsClientBackend with tracing API.

tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py b/tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend.py
similarity index 91%
rename from tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
rename to tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend.py
index 62426419bdc07504e10264d4b74b915761da93a8..e32cc12826edf5b11e5701eb2d1df39b688263c0 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tracing_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend.py
@@ -20,7 +20,7 @@ class TracingHasNotRunException(Exception):
 
 
 class TracingBackend(object):
-  def __init__(self, devtools_port, chrome_browser_backend):
+  def __init__(self, devtools_port, devtools_client_backend):
     self._inspector_websocket = inspector_websocket.InspectorWebsocket(
         self._ErrorHandler)
     self._inspector_websocket.RegisterDomain(
@@ -30,16 +30,12 @@ class TracingBackend(object):
         'ws://127.0.0.1:%i/devtools/browser' % devtools_port)
     self._tracing_data = []
     self._is_tracing_running = False
-    self._chrome_browser_backend = chrome_browser_backend
+    self._devtools_client_backend = devtools_client_backend
 
   @property
   def is_tracing_running(self):
     return self._is_tracing_running
 
-  @property
-  def _devtools_client(self):
-    return self._chrome_browser_backend.devtools_client
-
   def StartTracing(self, trace_options, custom_categories=None, timeout=10):
     """ Starts tracing on the first call and returns True. Returns False
         and does nothing on subsequent nested calls.
@@ -51,13 +47,13 @@ class TracingBackend(object):
     self._CheckNotificationSupported()
     #TODO(nednguyen): remove this when the stable branch pass 2118.
     if (trace_options.record_mode == tracing_options.RECORD_AS_MUCH_AS_POSSIBLE
-        and self._devtools_client.GetChromeBranchNumber()
-        and self._devtools_client.GetChromeBranchNumber() < 2118):
+        and self._devtools_client_backend.GetChromeBranchNumber()
+        and self._devtools_client_backend.GetChromeBranchNumber() < 2118):
       logging.warning(
           'Cannot use %s tracing mode on chrome browser with branch version %i,'
           ' (<2118) fallback to use %s tracing mode' % (
               trace_options.record_mode,
-              self._devtools_client.GetChromeBranchNumber(),
+              self._devtools_client_backend.GetChromeBranchNumber(),
               tracing_options.RECORD_UNTIL_FULL))
       trace_options.record_mode = tracing_options.RECORD_UNTIL_FULL
     req = {'method': 'Tracing.start'}