Add a switch to emit browser histograms.

chrome/browser/ui/startup/startup_browser_creator.cc

 // Copyright (c) 2012 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/ui/startup/startup_browser_creator.h"
 
 #include <algorithm>   // For max().
 #include <set>
 
 #include "apps/app_load_service.h"
 #include "apps/switches.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/environment.h"
+#include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/path_service.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/browser/app_mode/app_mode_utils.h"
 #include "chrome/browser/auto_launch_trial.h"
 #include "chrome/browser/automation/automation_provider.h"
 #include "chrome/browser/automation/automation_provider_list.h"
@@ skipping 188 matching lines @@
   Profile* profile_to_activate_;
   // Set once we attempted to activate a profile. We only get one shot at this.
   bool activated_profile_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileLaunchObserver);
 };
 
 base::LazyInstance<ProfileLaunchObserver> profile_launch_observer =
     LAZY_INSTANCE_INITIALIZER;
 
+// This function should only be called in the blocking pool.

[Alexei Svitkine (slow), 2013/11/13 19:04:32]

Nit: Have the comment actually briefly mention what this does.

[grt (UTC plus 2), 2013/11/14 05:08:51]

Done.

+void DumpBrowserHistograms(const base::FilePath& output_file) {
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  if (base::PathExists(output_file))
+    return;
+
+  std::string output_string;
+  base::StatisticsRecorder::WriteJSON(std::string(), &output_string);
+  if (output_string.size() <= INT_MAX) {
+    file_util::WriteFile(output_file, output_string.data(),
+                         static_cast<int>(output_string.size()));
+  }
+}
+
 }  // namespace
 
 StartupBrowserCreator::StartupBrowserCreator()
     : is_default_browser_dialog_suppressed_(false),
       show_main_browser_window_(true) {
 }
 
 StartupBrowserCreator::~StartupBrowserCreator() {}
 
 // static
@@ skipping 355 matching lines @@
 
     // Skip browser launch since app mode launches its app window.
     silent_launch = true;
   }
 #endif
 
 #if defined(TOOLKIT_VIEWS) && defined(USE_X11)
   ui::TouchFactory::SetTouchDeviceListFromCommandLine();
 #endif
 
+  if (!process_startup) {

[marja, 2013/11/13 15:37:34]

Doing some code searching, it seems process_startup is also false when we're
creating a new profile and launch it. In that case previously, silent_launch was
not set to true, and now you're setting it to true. That doesn't seem right.

[grt (UTC plus 2), 2013/11/14 05:08:51]

Indeed. Nice catch. I had meant for silent_launch only to be set if the new
switch was present. I've fixed the code and added a comment to this effect.

+    base::FilePath output_file(
+        command_line.GetSwitchValuePath(switches::kDumpBrowserHistograms));
+    if (!output_file.empty()) {
+      BrowserThread::PostBlockingPoolTask(
+          FROM_HERE,
+          base::Bind(&DumpBrowserHistograms, output_file));
+    }
+    silent_launch = true;
+  }
+
   // If we don't want to launch a new browser window or tab (in the case
   // of an automation request), we are done here.
   if (silent_launch)
     return true;
 
   // Check for --load-and-launch-app.
   if (command_line.HasSwitch(apps::kLoadAndLaunchApp) &&
       !IncognitoModePrefs::ShouldLaunchIncognito(
           command_line, last_used_profile->GetPrefs())) {
     CommandLine::StringType path = command_line.GetSwitchValueNative(
@@ skipping 139 matching lines @@
 
 // static
 bool StartupBrowserCreator::ActivatedProfile() {
   return profile_launch_observer.Get().activated_profile();
 }
 
 bool HasPendingUncleanExit(Profile* profile) {
   return profile->GetLastSessionExitType() == Profile::EXIT_CRASHED &&
       !profile_launch_observer.Get().HasBeenLaunched(profile);
 }