[Telemetry] Separate devtools functionality from tracing agent

This CL separates devtools functionality from tracing agent. Right now, ChromeTracingAgent is just a wrapper around ChromeDevtoolsTracingBackend. In the next CL, creating/removing the trace config file will be added to ChromeTracingAgent.

Design doc for platform-level tracing in telemetry:
https://docs.google.com/document/d/1Uv8SzOq2ugvzLiOcP85g7qPiaxwsn4tgOdxpe3YjUkM/edit?usp=sharing

BUG=515323

Review URL: https://codereview.chromium.org/1253003006

Cr-Commit-Position: refs/heads/master@{#341612}

5 files changed, 87 insertions, 66 deletions

diff --git a/tools/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py b/tools/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py
index ddb4b61..a75a2af 100644
--- a/tools/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py
+++ b/tools/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py
@@ -11,8 +11,7 @@ from telemetry import decorators
 from telemetry.internal.backends.chrome_inspector import devtools_http
 from telemetry.internal.backends.chrome_inspector import inspector_backend
 from telemetry.internal.backends.chrome_inspector import tracing_backend
-from telemetry.internal.platform.tracing_agent import (
-    chrome_devtools_tracing_agent)
+from telemetry.internal.platform.tracing_agent import chrome_tracing_agent
 from telemetry.timeline import trace_data as trace_data_module
 
 
@@ -67,8 +66,8 @@ class DevToolsClientBackend(object):
     self._devtools_context_map_backend = _DevToolsContextMapBackend(
         self._app_backend, self)
 
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(self, self._app_backend.platform_backend))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+      self, self._app_backend.platform_backend)
 
   @property
   def remote_port(self):
diff --git a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_agent.py b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py
index 827e2e1..b1345ad9 100644
--- a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_agent.py
+++ b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_backend.py
@@ -4,8 +4,6 @@
 import sys
 import traceback
 
-from telemetry.internal.platform import tracing_agent
-
 
 class ChromeTracingStartedError(Exception):
   pass
@@ -15,7 +13,7 @@ class ChromeTracingStoppedError(Exception):
   pass
 
 
-class ChromeDevtoolsTracingAgent(tracing_agent.TracingAgent):
+class ChromeDevtoolsTracingBackend(object):
   # A singleton map from platform backends to maps of uniquely-identifying
   # remote port (which may be the same as local port) to DevToolsClientBackend.
   # There is no guarantee that the devtools agent is still alive.
@@ -24,7 +22,7 @@ class ChromeDevtoolsTracingAgent(tracing_agent.TracingAgent):
   _is_tracing_running_for_platform_backend.setdefault(False)
 
   def __init__(self, platform_backend):
-    super(ChromeDevtoolsTracingAgent, self).__init__(platform_backend)
+    self._platform_backend = platform_backend
 
   @classmethod
   def _RemoveStaleDevToolsClient(cls, platform_backend):
diff --git a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_tracing_agent.py b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_tracing_agent.py
new file mode 100644
index 0000000..4e4fc13
--- /dev/null
+++ b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_tracing_agent.py
@@ -0,0 +1,32 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from telemetry.internal.platform import tracing_agent
+from telemetry.internal.platform.tracing_agent import (
+    chrome_devtools_tracing_backend)
+
+
+class ChromeTracingAgent(tracing_agent.TracingAgent):
+  def __init__(self, platform_backend):
+    super(ChromeTracingAgent, self).__init__(platform_backend)
+    self._chrome_devtools_tracing_backend = (
+      chrome_devtools_tracing_backend.ChromeDevtoolsTracingBackend(
+        platform_backend))
+
+  @classmethod
+  def RegisterDevToolsClient(cls, devtools_client_backend, platform_backend):
+    (chrome_devtools_tracing_backend.ChromeDevtoolsTracingBackend
+        .RegisterDevToolsClient(devtools_client_backend, platform_backend))
+
+  @classmethod
+  def IsSupported(cls, platform_backend):
+    return (chrome_devtools_tracing_backend.ChromeDevtoolsTracingBackend
+      .IsSupported(platform_backend))
+
+  def Start(self, trace_options, category_filter, timeout):
+    return self._chrome_devtools_tracing_backend.Start(
+        trace_options, category_filter, timeout)
+
+  def Stop(self, trace_data_builder):
+    self._chrome_devtools_tracing_backend.Stop(trace_data_builder)
diff --git a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_agent_unittest.py b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_tracing_agent_unittest.py
index 087f09a..837d84d 100644
--- a/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_devtools_tracing_agent_unittest.py
+++ b/tools/telemetry/telemetry/internal/platform/tracing_agent/chrome_tracing_agent_unittest.py
@@ -5,7 +5,8 @@
 import unittest
 
 from telemetry.internal.platform.tracing_agent import (
-    chrome_devtools_tracing_agent)
+    chrome_devtools_tracing_backend)
+from telemetry.internal.platform.tracing_agent import chrome_tracing_agent
 
 
 class FakePlatformBackend(object):
@@ -44,17 +45,15 @@ class FakeCategoryFilter(object):
     self.filter_string = 'foo'
 
 
-class ChromeDevtoolsTracingAgentUnittest(unittest.TestCase):
+class ChromeTracingAgentUnittest(unittest.TestCase):
   def setUp(self):
     self.platform1 = FakePlatformBackend()
     self.platform2 = FakePlatformBackend()
     self.platform3 = FakePlatformBackend()
 
   def StartTracing(self, platform_backend, enable_chrome_trace=True):
-    assert chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-        platform_backend)
-    agent = chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent(
-        platform_backend)
+    assert chrome_tracing_agent.ChromeTracingAgent.IsSupported(platform_backend)
+    agent = chrome_tracing_agent.ChromeTracingAgent(platform_backend)
     trace_options = FakeTraceOptions()
     trace_options.enable_chrome_trace = enable_chrome_trace
     agent.Start(trace_options, FakeCategoryFilter(), 10)
@@ -64,56 +63,50 @@ class ChromeDevtoolsTracingAgentUnittest(unittest.TestCase):
     tracing_agent.Stop(None)
 
   def testRegisterDevtoolsClient(self):
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(FakeDevtoolsClient(1), self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(FakeDevtoolsClient(2), self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(FakeDevtoolsClient(3), self.platform1))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(1), self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(2), self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(3), self.platform1)
 
     tracing_agent_of_platform1 = self.StartTracing(self.platform1)
 
     with self.assertRaises(
-        chrome_devtools_tracing_agent.ChromeTracingStartedError):
-      (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-          .RegisterDevToolsClient(FakeDevtoolsClient(4), self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(FakeDevtoolsClient(5), self.platform2))
+        chrome_devtools_tracing_backend.ChromeTracingStartedError):
+      chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(4), self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(5), self.platform2)
 
     self.StopTracing(tracing_agent_of_platform1)
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(FakeDevtoolsClient(6), self.platform1))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        FakeDevtoolsClient(6), self.platform1)
 
   def testIsSupport(self):
     self.assertFalse(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform1))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform1))
     self.assertFalse(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform2))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform2))
     self.assertFalse(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform3))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform3))
 
     devtool1 = FakeDevtoolsClient(1)
     devtool2 = FakeDevtoolsClient(2)
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool1, self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool2, self.platform2))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool1, self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool2, self.platform2)
     devtool2.is_alive = False
 
     # Chrome tracing is only supported on platform 1 since only platform 1 has
     # an alive devtool.
     self.assertTrue(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform1))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform1))
     self.assertFalse(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform2))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform2))
     self.assertFalse(
-        chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
-            self.platform3))
+        chrome_tracing_agent.ChromeTracingAgent.IsSupported(self.platform3))
 
   def testStartAndStopTracing(self):
     devtool1 = FakeDevtoolsClient(1)
@@ -121,19 +114,19 @@ class ChromeDevtoolsTracingAgentUnittest(unittest.TestCase):
     devtool3 = FakeDevtoolsClient(3)
     devtool4 = FakeDevtoolsClient(2)
     # Register devtools 1, 2, 3 on platform1 and devtool 4 on platform 2
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool1, self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool2, self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool3, self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool4, self.platform2))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool1, self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool2, self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool3, self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool4, self.platform2)
     devtool2.is_alive = False
 
     tracing_agent1 = self.StartTracing(self.platform1)
     with self.assertRaises(
-        chrome_devtools_tracing_agent.ChromeTracingStartedError):
+        chrome_devtools_tracing_backend.ChromeTracingStartedError):
       self.StartTracing(self.platform1)
 
     self.assertTrue(devtool1.tracing_started)
@@ -161,10 +154,10 @@ class ChromeDevtoolsTracingAgentUnittest(unittest.TestCase):
     devtool1 = FakeDevtoolsClient(1)
     devtool2 = FakeDevtoolsClient(2)
     # Register devtools 1, 2 on platform 1
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool1, self.platform1))
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool2, self.platform1))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool1, self.platform1)
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool2, self.platform1)
     tracing_agent1 = self.StartTracing(self.platform1)
 
     self.assertTrue(devtool1.tracing_started)
@@ -172,15 +165,15 @@ class ChromeDevtoolsTracingAgentUnittest(unittest.TestCase):
 
     devtool2.will_raise_exception_in_stop_tracing = True
     with self.assertRaises(
-        chrome_devtools_tracing_agent.ChromeTracingStoppedError):
+        chrome_devtools_tracing_backend.ChromeTracingStoppedError):
       self.StopTracing(tracing_agent1)
 
     devtool1.is_alive = False
     devtool2.is_alive = False
     # Register devtools 3 on platform 1 should not raise any exception.
     devtool3 = FakeDevtoolsClient(3)
-    (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent
-        .RegisterDevToolsClient(devtool3, self.platform1))
+    chrome_tracing_agent.ChromeTracingAgent.RegisterDevToolsClient(
+        devtool3, self.platform1)
 
     # Start & Stop tracing on platform 1 should work just fine.
     tracing_agent2 = self.StartTracing(self.platform1)
diff --git a/tools/telemetry/telemetry/internal/platform/tracing_controller_backend.py b/tools/telemetry/telemetry/internal/platform/tracing_controller_backend.py
index 1e79c4d..ee318bd 100644
--- a/tools/telemetry/telemetry/internal/platform/tracing_controller_backend.py
+++ b/tools/telemetry/telemetry/internal/platform/tracing_controller_backend.py
@@ -6,8 +6,7 @@ import os
 
 from telemetry.core import util
 from telemetry.internal.platform import tracing_agent
-from telemetry.internal.platform.tracing_agent import (
-    chrome_devtools_tracing_agent)
+from telemetry.internal.platform.tracing_agent import chrome_tracing_agent
 from telemetry.timeline import trace_data as trace_data_module
 from telemetry.timeline import tracing_category_filter
 from telemetry.timeline import tracing_options
@@ -26,7 +25,7 @@ class TracingControllerBackend(object):
     self._platform_backend = platform_backend
     self._current_trace_options = None
     self._current_category_filter = None
-    self._current_chrome_devtools_tracing_agent = None
+    self._current_chrome_tracing_agent = None
     self._supported_agents_classes = [
         agent_classes for agent_classes in _IterAllTracingAgentClasses() if
         agent_classes.IsSupported(platform_backend)]
@@ -47,12 +46,12 @@ class TracingControllerBackend(object):
     # Hack: chrome tracing agent depends on the number of alive chrome devtools
     # processes, rather platform, hence we add it to the list of supported
     # agents here if it was not added.
-    if (chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
+    if (chrome_tracing_agent.ChromeTracingAgent.IsSupported(
         self._platform_backend) and
-        not chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent in
+        not chrome_tracing_agent.ChromeTracingAgent in
         self._supported_agents_classes):
       self._supported_agents_classes.append(
-          chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent)
+          chrome_tracing_agent.ChromeTracingAgent)
 
     for agent_class in self._supported_agents_classes:
       agent = agent_class(self._platform_backend)
@@ -70,7 +69,7 @@ class TracingControllerBackend(object):
     return trace_data_builder.AsData()
 
   def IsChromeTracingSupported(self):
-    return chrome_devtools_tracing_agent.ChromeDevtoolsTracingAgent.IsSupported(
+    return chrome_tracing_agent.ChromeTracingAgent.IsSupported(
         self._platform_backend)
 
   @property