Background tracing: Tracing scenarios can now enable/disable Blink features, for A/B testing purpos…

content/browser/tracing/background_tracing_manager_browsertest.cc

 // 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.
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/pattern.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/tracing/background_tracing_manager_impl.h"
 #include "content/browser/tracing/background_tracing_rule.h"
+#include "content/public/common/content_switches.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/public/test/content_browser_test_utils.h"
 #include "content/public/test/test_utils.h"
 #include "third_party/zlib/zlib.h"
 
 namespace content {
 
 class BackgroundTracingManagerBrowserTest : public ContentBrowserTest {
  public:
   BackgroundTracingManagerBrowserTest() {}
@@ skipping 387 matching lines @@
     BackgroundTracingManager::GetInstance()->TriggerNamedEvent(
         handle2,
         base::Bind(&StartedFinalizingCallback, base::Closure(), false));
 
     run_loop.Run();
 
     EXPECT_TRUE(upload_config_wrapper.get_receive_count() == 1);
   }
 }
 
+// This tests that toggling Blink scenarios in the config alters the
+// command-line.
+IN_PROC_BROWSER_TEST_F(BackgroundTracingManagerBrowserTest,
+                       ToggleBlinkScenarios) {
+  {
+    SetupBackgroundTracingManager();
+
+    base::RunLoop run_loop;
+    BackgroundTracingManagerUploadConfigWrapper upload_config_wrapper(
+        run_loop.QuitClosure());
+
+    base::DictionaryValue dict;
+    dict.SetString("mode", "PREEMPTIVE_TRACING_MODE");
+    dict.SetString("category", "BENCHMARK");
+
+    scoped_ptr<base::ListValue> rules_list(new base::ListValue());
+    {
+      scoped_ptr<base::DictionaryValue> rules_dict(new base::DictionaryValue());
+      rules_dict->SetString("rule", "MONITOR_AND_DUMP_WHEN_TRIGGER_NAMED");
+      rules_dict->SetString("trigger_name", "test2");
+      rules_list->Append(rules_dict.Pass());
+    }
+
+    dict.Set("configs", rules_list.Pass());
+    dict.SetString("enable_blink_features", "FasterWeb1,FasterWeb2");
+    dict.SetString("disable_blink_features", "SlowerWeb1,SlowerWeb2");
+    scoped_ptr<BackgroundTracingConfig> config(
+        BackgroundTracingConfigImpl::FromDict(&dict));
+    EXPECT_TRUE(config);
+
+    bool scenario_activated =
+        BackgroundTracingManager::GetInstance()->SetActiveScenario(
+            config.Pass(), upload_config_wrapper.get_receive_callback(),
+            BackgroundTracingManager::NO_DATA_FILTERING);
+
+    EXPECT_TRUE(scenario_activated);

[shatch, 2015/10/26 15:24:45]

Maybe set the command line first to exercise the paths where it doesn't get
activated.

[oystein (OOO til 10th of July), 2015/10/26 18:28:39]

Done; added second test.

+
+    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+    EXPECT_TRUE(command_line);
+
+    EXPECT_EQ(command_line->GetSwitchValueASCII(switches::kEnableBlinkFeatures),
+              "FasterWeb1,FasterWeb2");
+    EXPECT_EQ(
+        command_line->GetSwitchValueASCII(switches::kDisableBlinkFeatures),
+        "SlowerWeb1,SlowerWeb2");
+  }
+}
+
 // This tests that delayed histogram triggers triggers work as expected
 // with preemptive scenarios.
 IN_PROC_BROWSER_TEST_F(BackgroundTracingManagerBrowserTest,
                        CallPreemptiveTriggerWithDelay) {
   {
     SetupBackgroundTracingManager();
 
     base::RunLoop run_loop;
     BackgroundTracingManagerUploadConfigWrapper upload_config_wrapper(
         run_loop.QuitClosure());
@@ skipping 480 matching lines @@
     BackgroundTracingManager::GetInstance()->TriggerNamedEvent(
         handle, base::Bind(&StartedFinalizingCallback, base::Closure(), false));
 
     run_loop.Run();
 
     EXPECT_TRUE(upload_config_wrapper.get_receive_count() == 1);
   }
 }
 
 }  // namespace content