Stability file flushing: replace experiment by parameter

chrome/browser/chrome_browser_field_trials_desktop.cc

 // Copyright 2013 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 "chrome/browser/chrome_browser_field_trials_desktop.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include <map>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/debug/activity_tracker.h"
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
+#include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "chrome/browser/features.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/browser_watcher/features.h"
 #include "components/browser_watcher/stability_debugging.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/common/content_switches.h"
@@ skipping 149 matching lines @@
 
     // Record information about chrome's module. We want this to be done early.
     RecordChromeModuleInfo(global_tracker);
 
     // Trigger a flush of the memory mapped file to maximize the chances of
     // having a minimal amount of content in the stability file, even if
     // the system crashes or loses power. Note: this does not flush the file
     // metadata nor does it wait for the changes to be flushed to disk before
     // returning. This is an expensive operation. Run as an experiment to
     // measure the effect on performance and collection.
-    if (base::FeatureList::IsEnabled(
-            browser_watcher::kStabilityDebuggingFlushFeature)) {
+    const std::string init_flush_param = base::GetFieldTrialParamValueByFeature(

[rkaplow, 2017/03/13 15:38:00]

using GetFieldTrialParamByFeatureAsBool will make your life simpler

[manzagop (departed), 2017/03/13 17:51:26]

Done.

+        browser_watcher::kStabilityDebuggingFeature,
+        browser_watcher::kInitFlushParam);
+    if (base::LowerCaseEqualsASCII(init_flush_param, "true")) {
       ::FlushViewOfFile(global_tracker->allocator()->data(), 0U);
     }
   }
 }
 #endif  // defined(OS_WIN)
 
 }  // namespace
 
 void SetupDesktopFieldTrials() {
   prerender::ConfigurePrerender();
   SetupStunProbeTrial();
 #if defined(OS_WIN)
   SetupStabilityDebugging();
   base::FeatureList::IsEnabled(features::kModuleDatabase);
 #endif  // defined(OS_WIN)
   // Activate the experiment as early as possible to increase its visibility
   // (e.g. the likelihood of its presence in the serialized system profile).
   // This also needs to happen before the browser rendez-vous attempt
   // (NotifyOtherProcessOrCreate) in PreMainMessageLoopRun so the corresponding
   // metrics are tagged.
   base::FeatureList::IsEnabled(features::kDesktopFastShutdown);
 }
 
 }  // namespace chrome