[Merge M48] Add Startup.TimeSinceLastStartup histogram.

This histogram shows the time between 2 consecutive startups.

BUG=547794

Review URL: https://codereview.chromium.org/1558203003

Cr-Commit-Position: refs/heads/master@{#368354}
(cherry picked from commit 44cd7819dc6be0e640b6a1e03964d61210415a12)

Conflicts:
	components/startup_metric_utils.gypi
	components/startup_metric_utils/browser/BUILD.gn
	components/startup_metric_utils/browser/startup_metric_utils.cc
	components/startup_metric_utils/browser/startup_metric_utils.h
	tools/metrics/histograms/histograms.xml

R=fdoray@chromium.org
TBR=fdoray@chromium.org

Review URL: https://codereview.chromium.org/1667903003 .

Cr-Commit-Position: refs/branch-heads/2564@{#664}
Cr-Branched-From: 1283eca15bd9f772387f75241576cde7bdec7f54-refs/heads/master@{#359700}

7 files changed, 76 insertions, 0 deletions

diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index 920bb2c..daed827 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -769,6 +769,9 @@ void ChromeBrowserMainParts::RecordBrowserStartupTime() {
   // Record collected startup metrics.
   startup_metric_utils::RecordBrowserMainMessageLoopStart(
       base::TimeTicks::Now(), is_first_run);
+
+  startup_metric_utils::RecordTimeSinceLastStartup(
+      g_browser_process->local_state());
 }
 
 // -----------------------------------------------------------------------------
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 5fe77e7c..d8b8465 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -81,6 +81,7 @@
 #include "components/rappor/rappor_service.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
 #include "components/ssl_config/ssl_config_service_manager.h"
+#include "components/startup_metric_utils/browser/startup_metric_utils.h"
 #include "components/sync_driver/sync_prefs.h"
 #include "components/syncable_prefs/pref_service_syncable.h"
 #include "components/translate/core/browser/translate_prefs.h"
@@ -262,6 +263,7 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
   RegisterScreenshotPrefs(registry);
   SigninManagerFactory::RegisterPrefs(registry);
   ssl_config::SSLConfigServiceManager::RegisterPrefs(registry);
+  startup_metric_utils::RegisterPrefs(registry);
   web_resource::PromoResourceService::RegisterPrefs(registry);
 
 #if defined(ENABLE_AUTOFILL_DIALOG)
diff --git a/components/startup_metric_utils.gypi b/components/startup_metric_utils.gypi
index f70e7a0..ad01dbb 100644
--- a/components/startup_metric_utils.gypi
+++ b/components/startup_metric_utils.gypi
@@ -9,6 +9,7 @@
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
+        '../base/base.gyp:base_prefs',
       ],
       'include_dirs': [
         '..',
diff --git a/components/startup_metric_utils/browser/BUILD.gn b/components/startup_metric_utils/browser/BUILD.gn
index 258e210..dfcf1e5 100644
--- a/components/startup_metric_utils/browser/BUILD.gn
+++ b/components/startup_metric_utils/browser/BUILD.gn
@@ -10,5 +10,6 @@ source_set("browser") {
 
   deps = [
     "//base",
+    "//base:prefs",
   ]
 }
diff --git a/components/startup_metric_utils/browser/startup_metric_utils.cc b/components/startup_metric_utils/browser/startup_metric_utils.cc
index b1d413f..c83dc1a 100644
--- a/components/startup_metric_utils/browser/startup_metric_utils.cc
+++ b/components/startup_metric_utils/browser/startup_metric_utils.cc
@@ -9,6 +9,9 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service.h"
+#include "base/process/process_info.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
@@ -23,6 +26,9 @@ namespace startup_metric_utils {
 
 namespace {
 
+const char kLastStartupTimestampPref[] =
+    "startup_metric.last_startup_timestamp";
+
 // Mark as volatile to defensively make sure usage is thread-safe.
 // Note that at the time of this writing, access is only on the UI thread.
 volatile bool g_non_browser_ui_displayed = false;
@@ -159,6 +165,9 @@ bool GetHardFaultCountForCurrentProcess(uint32_t* hard_fault_count,
 
 #endif  // defined(OS_WIN)
 
+#define UMA_HISTOGRAM_TIME_IN_MINUTES_MONTH_RANGE(name, sample) \
+  UMA_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1,                  \
+                              base::TimeDelta::FromDays(30).InMinutes(), 50)
 
 // Helper macro for splitting out an UMA histogram based on cold or warm start.
 // |type| is the histogram type, and corresponds to an UMA macro like
@@ -378,6 +387,11 @@ base::TimeTicks ExeMainEntryPointTicks() {
 
 }  // namespace
 
+void RegisterPrefs(PrefRegistrySimple* registry) {
+  DCHECK(registry);
+  registry->RegisterInt64Pref(kLastStartupTimestampPref, 0);
+}
+
 bool WasNonBrowserUIDisplayed() {
   return g_non_browser_ui_displayed;
 }
@@ -472,6 +486,39 @@ void RecordBrowserMainMessageLoopStart(const base::TimeTicks& ticks,
   }
 }
 
+void RecordTimeSinceLastStartup(PrefService* pref_service) {
+#if defined(OS_MACOSX) || defined(OS_WIN) || defined(OS_LINUX)
+  DCHECK(pref_service);
+
+  // Get the timestamp of the current startup.
+  const base::Time process_start_time =
+      base::CurrentProcessInfo::CreationTime();
+
+  // Get the timestamp of the last startup from |pref_service|.
+  const int64_t last_startup_timestamp_internal =
+      pref_service->GetInt64(kLastStartupTimestampPref);
+  if (last_startup_timestamp_internal != 0) {
+    // Log the Startup.TimeSinceLastStartup histogram.
+    const base::Time last_startup_timestamp =
+        base::Time::FromInternalValue(last_startup_timestamp_internal);
+    const base::TimeDelta time_since_last_startup =
+        process_start_time - last_startup_timestamp;
+    const int minutes_since_last_startup = time_since_last_startup.InMinutes();
+
+    // Ignore negative values, which can be caused by system clock changes.
+    if (minutes_since_last_startup >= 0) {
+      UMA_HISTOGRAM_WITH_STARTUP_TEMPERATURE(
+          UMA_HISTOGRAM_TIME_IN_MINUTES_MONTH_RANGE,
+          "Startup.TimeSinceLastStartup", minutes_since_last_startup);
+    }
+  }
+
+  // Write the timestamp of the current startup in |pref_service|.
+  pref_service->SetInt64(kLastStartupTimestampPref,
+                         process_start_time.ToInternalValue());
+#endif  // defined(OS_MACOSX) || defined(OS_WIN) || defined(OS_LINUX)
+}
+
 void RecordBrowserWindowDisplay(const base::TimeTicks& ticks) {
   static bool is_first_call = true;
   if (!is_first_call || ticks.is_null())
diff --git a/components/startup_metric_utils/browser/startup_metric_utils.h b/components/startup_metric_utils/browser/startup_metric_utils.h
index c0391ff..fde9f36 100644
--- a/components/startup_metric_utils/browser/startup_metric_utils.h
+++ b/components/startup_metric_utils/browser/startup_metric_utils.h
@@ -9,6 +9,9 @@
 
 #include "base/time/time.h"
 
+class PrefRegistrySimple;
+class PrefService;
+
 // Utility functions to support metric collection for browser startup. Timings
 // should use TimeTicks whenever possible. OS-provided timings are still
 // received as Time out of cross-platform support necessity but are converted to
@@ -36,6 +39,9 @@ enum StartupTemperature {
   UNDETERMINED_STARTUP_TEMPERATURE
 };
 
+// Registers startup related prefs in |registry|.
+void RegisterPrefs(PrefRegistrySimple* registry);
+
 // Returns true if any UI other than the browser window has been displayed
 // so far.  Useful to test if UI has been displayed before the first browser
 // window was shown, which would invalidate any surrounding timing metrics.
@@ -68,6 +74,13 @@ void RecordExeMainEntryPointTime(const base::Time& time);
 void RecordBrowserMainMessageLoopStart(const base::TimeTicks& ticks,
                                        bool is_first_run);
 
+// Logs the Startup.TimeSinceLastStartup histogram. Obtains the timestamp of the
+// last startup from |pref_service| and overwrites it with the timestamp of the
+// current startup. If the startup temperature has been set by
+// RecordBrowserMainMessageLoopStart, the time since last startup is also logged
+// to an histogram suffixed with the startup temperature.
+void RecordTimeSinceLastStartup(PrefService* pref_service);
+
 // Call this with the time when the first browser window became visible.
 void RecordBrowserWindowDisplay(const base::TimeTicks& ticks);
 
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 75fd853..f3f225d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -45799,6 +45799,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Startup.TimeSinceLastStartup" units="minutes">
+  <owner>fdoray@chromium.org</owner>
+  <summary>
+    Time elapsed since the last startup that went up to the main message loop
+    start. This is recorded just before the main message loop starts.
+  </summary>
+</histogram>
+
 <histogram name="Startup.WarmStartTimeFromRemoteProcessStart"
     units="milliseconds">
   <owner>jeremy@chromium.org</owner>
@@ -82290,6 +82298,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Startup.LoadTime.ProcessCreateToDllMain"/>
   <affected-histogram name="Startup.LoadTime.ProcessCreateToExeMain"/>
   <affected-histogram name="Startup.SystemUptime"/>
+  <affected-histogram name="Startup.TimeSinceLastStartup"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="StartupTimeBombAlarm" separator=".">