DevTools: Do not start tracing in renderer process explicitly.

The tracing is now initiated by the browser process. There's no need
to start it in renderer anymore. TracingStartedInPage event is not
going to be produced anymore. It has been replaced with TracingStartedInBrowser.

Change-Id: I9e7759f7f792421d3f32fd21e82066e13a4901dc
Reviewed-on: https://chromium-review.googlesource.com/1182287
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584797}

content/browser/devtools/protocol/tracing_handler.cc

@@ -404,11 +404,6 @@ void TracingHandler::Start(Maybe<std::string> categories,
                                                    options.fromMaybe(""));
   }
 
-  // If inspected target is a render process Tracing.start will be handled by
-  // tracing agent in the renderer.
-  if (frame_tree_node_)
-    callback->fallThrough();
-
   SetupProcessFilter(nullptr);
 
   TracingController::GetInstance()->StartTracing(
@@ -462,14 +457,12 @@ void TracingHandler::OnProcessReady(RenderProcessHost* process_host) {
       trace_config_, base::RepeatingCallback<void()>());
 }
 
-void TracingHandler::End(std::unique_ptr<EndCallback> callback) {
+Response TracingHandler::End() {
   // Startup tracing triggered by --trace-config-file is a special case, where
   // tracing is started automatically upon browser startup and can be stopped
   // via DevTools.
-  if (!did_initiate_recording_ && !IsStartupTracingActive()) {
-    callback->sendFailure(Response::Error("Tracing is not started"));
-    return;
-  }
+  if (!did_initiate_recording_ && !IsStartupTracingActive())
+    return Response::Error("Tracing is not started");
 
   scoped_refptr<TracingController::TraceDataEndpoint> endpoint;
   if (return_as_stream_) {
@@ -488,12 +481,8 @@ void TracingHandler::End(std::unique_ptr<EndCallback> callback) {
     endpoint = new DevToolsTraceEndpointProxy(weak_factory_.GetWeakPtr());
     StopTracing(endpoint, tracing::mojom::kChromeTraceEventLabel);
   }
-  // If inspected target is a render process Tracing.end will be handled by
-  // tracing agent in the renderer.
-  if (frame_tree_node_)
-    callback->fallThrough();
-  else
-    callback->sendSuccess();
+
+  return Response::OK();
 }
 
 void TracingHandler::GetCategories(
@@ -508,7 +497,6 @@ void TracingHandler::OnRecordingEnabled(
     std::unique_ptr<StartCallback> callback) {
   EmitFrameTree();
 
-  if (!frame_tree_node_)
   callback->sendSuccess();
 
   bool screenshot_enabled;

content/browser/devtools/protocol/tracing_handler.h

@@ -69,7 +69,7 @@ class TracingHandler : public DevToolsDomainHandler, public Tracing::Backend {
              Maybe<std::string> transfer_compression,
              Maybe<Tracing::TraceConfig> config,
              std::unique_ptr<StartCallback> callback) override;
-  void End(std::unique_ptr<EndCallback> callback) override;
+  Response End() override;
   void GetCategories(std::unique_ptr<GetCategoriesCallback> callback) override;
   void RequestMemoryDump(
       std::unique_ptr<RequestMemoryDumpCallback> callback) override;

content/browser/devtools/protocol_config.json

@@ -85,7 +85,7 @@
             },
             {
                 "domain": "Tracing",
-                "async": ["start", "end", "getCategories", "requestMemoryDump"]
+                "async": ["start", "getCategories", "requestMemoryDump"]
             }
         ]
     },

third_party/WebKit/LayoutTests/http/tests/devtools/tracing-session-id-expected.txt

 Tests that Tracing agent returns a session id upon a start that is matching one issued in trace events.
 
-Got DevTools metadata event: TracingStartedInPage
+Got DevTools metadata event: TracingStartedInBrowser
 Got DevTools metadata event: SetLayerTreeId
 

third_party/WebKit/LayoutTests/http/tests/devtools/tracing-session-id.js

@@ -19,20 +19,16 @@
 
   await PerformanceTestRunner.invokeAsyncWithTimeline('waitForRaf');
 
-  PerformanceTestRunner.tracingModel().sortedProcesses().forEach(function(process) {
-    process.sortedThreads().forEach(function(thread) {
-      thread.events().forEach(processEvent);
-    });
-  });
+  let frameId = '';
+  PerformanceTestRunner.tracingModel().sortedProcesses().forEach(process =>
+    process.sortedThreads().forEach(thread => thread.events().forEach(processEvent))
+  );
   TestRunner.completeTest();
 
-  var frameId = '';
-
   function processEvent(event) {
     if (!event.hasCategory(SDK.TracingModel.DevToolsMetadataEventCategory))
       return;
-
-    if (event.name === TimelineModel.TimelineModel.RecordType.TracingStartedInPage) {
+    if (event.name === TimelineModel.TimelineModel.DevToolsMetadataEvent.TracingStartedInBrowser) {
       TestRunner.addResult('Got DevTools metadata event: ' + event.name);
       frameId = event.args['data']['frames'][0]['frame'];
     } else if (event.name === TimelineModel.TimelineModel.RecordType.SetLayerTreeId) {

third_party/blink/renderer/core/exported/web_dev_tools_agent_impl.cc

@@ -76,7 +76,6 @@
 #include "third_party/blink/renderer/core/inspector/inspector_resource_content_loader.h"
 #include "third_party/blink/renderer/core/inspector/inspector_session.h"
 #include "third_party/blink/renderer/core/inspector/inspector_task_runner.h"
-#include "third_party/blink/renderer/core/inspector/inspector_tracing_agent.h"
 #include "third_party/blink/renderer/core/inspector/inspector_worker_agent.h"
 #include "third_party/blink/renderer/core/inspector/main_thread_debugger.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
@@ -216,7 +215,6 @@ class WebDevToolsAgentImpl::Session : public GarbageCollectedFinalized<Session>,
   InspectorSession* inspector_session() { return inspector_session_.Get(); }
   InspectorNetworkAgent* network_agent() { return network_agent_.Get(); }
   InspectorPageAgent* page_agent() { return page_agent_.Get(); }
-  InspectorTracingAgent* tracing_agent() { return tracing_agent_.Get(); }
   InspectorOverlayAgent* overlay_agent() { return overlay_agent_.Get(); }
 
  private:
@@ -252,7 +250,6 @@ class WebDevToolsAgentImpl::Session : public GarbageCollectedFinalized<Session>,
   Member<InspectorSession> inspector_session_;
   Member<InspectorNetworkAgent> network_agent_;
   Member<InspectorPageAgent> page_agent_;
-  Member<InspectorTracingAgent> tracing_agent_;
   Member<InspectorOverlayAgent> overlay_agent_;
   bool detached_ = false;
 
@@ -339,7 +336,6 @@ void WebDevToolsAgentImpl::Session::Trace(blink::Visitor* visitor) {
   visitor->Trace(inspector_session_);
   visitor->Trace(network_agent_);
   visitor->Trace(page_agent_);
-  visitor->Trace(tracing_agent_);
   visitor->Trace(overlay_agent_);
 }
 
@@ -449,9 +445,6 @@ void WebDevToolsAgentImpl::Session::InitializeInspectorSession(
   inspector_session_->Append(
       new InspectorWorkerAgent(inspected_frames, nullptr));
 
-  tracing_agent_ = new InspectorTracingAgent(inspected_frames);
-  inspector_session_->Append(tracing_agent_);
-
   page_agent_ = InspectorPageAgent::Create(
       inspected_frames, agent_, agent_->resource_content_loader_.Get(),
       inspector_session_->V8Session());

third_party/blink/renderer/core/inspector/BUILD.gn

@@ -85,8 +85,6 @@ blink_core_sources("inspector") {
     "inspector_task_runner.h",
     "inspector_trace_events.cc",
     "inspector_trace_events.h",
-    "inspector_tracing_agent.cc",
-    "inspector_tracing_agent.h",
     "inspector_worker_agent.cc",
     "inspector_worker_agent.h",
     "main_thread_debugger.cc",

third_party/blink/renderer/core/inspector/inspector_protocol_config.json

@@ -71,11 +71,6 @@
                 "domain": "Memory",
                 "include": ["getDOMCounters", "startSampling", "stopSampling", "getSamplingProfile", "getAllTimeSamplingProfile"]
             },
-            {
-                "domain": "Tracing",
-                "include": ["start", "end"],
-                "async": ["start", "end"]
-            },
             {
                 "domain": "Page",
                 "exclude": ["getNavigationHistory", "navigateToHistoryEntry", "captureScreenshot", "screencastFrameAck", "handleJavaScriptDialog", "setColorPickerEnabled",

third_party/blink/renderer/core/inspector/inspector_tracing_agent.cc

-// Copyright 2014 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.
-
-#include "third_party/blink/renderer/core/inspector/inspector_tracing_agent.h"
-
-#include "third_party/blink/renderer/core/frame/local_frame.h"
-#include "third_party/blink/renderer/core/inspector/identifiers_factory.h"
-#include "third_party/blink/renderer/core/inspector/inspected_frames.h"
-#include "third_party/blink/renderer/core/inspector/inspector_trace_events.h"
-#include "third_party/blink/renderer/platform/instrumentation/tracing/trace_event.h"
-
-namespace blink {
-
-using protocol::Maybe;
-using protocol::Response;
-
-namespace {
-const char kDevtoolsMetadataEventCategory[] =
-    TRACE_DISABLED_BY_DEFAULT("devtools.timeline");
-}
-
-InspectorTracingAgent::InspectorTracingAgent(InspectedFrames* inspected_frames)
-    : session_id_(&agent_state_, /*default_value=*/ WTF::String()),
-      inspected_frames_(inspected_frames) {}
-
-InspectorTracingAgent::~InspectorTracingAgent() {}
-
-void InspectorTracingAgent::Trace(blink::Visitor* visitor) {
-  visitor->Trace(inspected_frames_);
-  InspectorBaseAgent::Trace(visitor);
-}
-
-void InspectorTracingAgent::Restore() {
-  if (IsStarted())
-    EmitMetadataEvents();
-}
-
-void InspectorTracingAgent::start(Maybe<String> categories,
-                                  Maybe<String> options,
-                                  Maybe<double> buffer_usage_reporting_interval,
-                                  Maybe<String> transfer_mode,
-                                  Maybe<String> transfer_compression,
-                                  Maybe<protocol::Tracing::TraceConfig> config,
-                                  std::unique_ptr<StartCallback> callback) {
-  DCHECK(!IsStarted());
-  if (config.isJust()) {
-    callback->sendFailure(Response::Error(
-        "Using trace config on renderer targets is not supported yet."));
-    return;
-  }
-
-  session_id_.Set(IdentifiersFactory::CreateIdentifier());
-
-  // Tracing is already started by DevTools TracingHandler::Start for the
-  // renderer target in the browser process. It will eventually start tracing
-  // in the renderer process via IPC. But we still need a redundant enable here
-  // for EmitMetadataEvents, at which point we are not sure if tracing
-  // is already started in the renderer process.
-  TraceEvent::EnableTracing(categories.fromMaybe(String()));
-
-  EmitMetadataEvents();
-  callback->sendSuccess();
-}
-
-void InspectorTracingAgent::end(std::unique_ptr<EndCallback> callback) {
-  TraceEvent::DisableTracing();
-  InnerDisable();
-  callback->sendSuccess();
-}
-
-bool InspectorTracingAgent::IsStarted() const {
-  return !session_id_.Get().IsEmpty();
-}
-
-void InspectorTracingAgent::EmitMetadataEvents() {
-  TRACE_EVENT_INSTANT1(kDevtoolsMetadataEventCategory, "TracingStartedInPage",
-                       TRACE_EVENT_SCOPE_THREAD, "data",
-                       InspectorTracingStartedInFrame::Data(
-                           session_id_.Get(), inspected_frames_->Root()));
-}
-
-Response InspectorTracingAgent::disable() {
-  InnerDisable();
-  return Response::OK();
-}
-
-void InspectorTracingAgent::InnerDisable() {
-  session_id_.Clear();
-}
-
-}  // namespace blink

third_party/blink/renderer/core/inspector/inspector_tracing_agent.h

-/*
- * Copyright 2014 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.
- */
-
-#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_INSPECTOR_INSPECTOR_TRACING_AGENT_H_
-#define THIRD_PARTY_BLINK_RENDERER_CORE_INSPECTOR_INSPECTOR_TRACING_AGENT_H_
-
-#include "base/macros.h"
-#include "third_party/blink/renderer/core/core_export.h"
-#include "third_party/blink/renderer/core/inspector/inspector_base_agent.h"
-#include "third_party/blink/renderer/core/inspector/protocol/Tracing.h"
-#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
-
-namespace blink {
-
-class InspectedFrames;
-
-class CORE_EXPORT InspectorTracingAgent final
-    : public InspectorBaseAgent<protocol::Tracing::Metainfo> {
- public:
-  explicit InspectorTracingAgent(InspectedFrames*);
-  ~InspectorTracingAgent() override;
-
-  void Trace(blink::Visitor*) override;
-
-  // Base agent methods.
-  void Restore() override;
-  protocol::Response disable() override;
-
-  // Protocol method implementations.
-  void start(protocol::Maybe<String> categories,
-             protocol::Maybe<String> options,
-             protocol::Maybe<double> buffer_usage_reporting_interval,
-             protocol::Maybe<String> transfer_mode,
-             protocol::Maybe<String> transfer_compression,
-             protocol::Maybe<protocol::Tracing::TraceConfig>,
-             std::unique_ptr<StartCallback>) override;
-  void end(std::unique_ptr<EndCallback>) override;
-
- private:
-  void EmitMetadataEvents();
-  void InnerDisable();
-  bool IsStarted() const;
-
-  InspectorAgentState::String session_id_;
-  Member<InspectedFrames> inspected_frames_;
-
-  DISALLOW_COPY_AND_ASSIGN(InspectorTracingAgent);
-};
-
-}  // namespace blink
-
-#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_INSPECTOR_INSPECTOR_TRACING_AGENT_H_