Flush stability file after initialization

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
 
@@ skipping 97 matching lines @@
 
   global_tracker->RecordModuleInfo(module);
 }
 
 void SetupStabilityDebugging() {
   if (!base::FeatureList::IsEnabled(
           browser_watcher::kStabilityDebuggingFeature)) {
     return;
   }
 
+  SCOPED_UMA_HISTOGRAM_TIMER("ActivityTracker.Record.SetupTime");
+
   // TODO(bcwhite): Adjust these numbers once there is real data to show
   // just how much of an arena is necessary.
   const size_t kMemorySize = 1 << 20;  // 1 MiB
   const int kStackDepth = 4;
   const uint64_t kAllocatorId = 0;
 
   // Ensure the stability directory exists and determine the stability file's
   // path.
   base::FilePath user_data_dir;
   if (!base::PathService::Get(chrome::DIR_USER_DATA, &user_data_dir) ||
@@ skipping 40 matching lines @@
     global_data.SetString(browser_watcher::kStabilitySpecialBuild,
                           special_build);
 #if defined(ARCH_CPU_X86)
     global_data.SetString(browser_watcher::kStabilityPlatform, "Win32");
 #elif defined(ARCH_CPU_X86_64)
     global_data.SetString(browser_watcher::kStabilityPlatform, "Win64");
 #endif
 
     // 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)) {
+      ::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