[Merge M49] Add Startup.SameVersionStartupCount histogram

components/startup_metric_utils/browser/startup_metric_utils.h

 // 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.
 
 #ifndef COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_UTILS_H_
 #define COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_UTILS_H_
 
 #include <stdint.h>
 #include <string>
 
 #include "base/time/time.h"
 #include "build/build_config.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
 // TimeTicks as soon as possible in an attempt to reduce the potential skew
 // between the two basis. See crbug.com/544131 for reasoning.
 
 namespace startup_metric_utils {
 
 // An enumeration of startup temperatures. This must be kept in sync with the
 // UMA StartupType enumeration defined in histograms.xml.
 enum StartupTemperature {
-  // The startup was a cold start: nearly all of the Chrome binaries and
-  // resources were brought into memory using hard faults.
+  // The startup was a cold start: nearly all of the binaries and resources were
+  // brought into memory using hard faults.
   COLD_STARTUP_TEMPERATURE = 0,
-  // The startup was a warm start: the Chrome binaries and resources were
-  // mostly already resident in memory and effectively no hard faults were
-  // observed.
+  // The startup was a warm start: the binaries and resources were mostly
+  // already resident in memory and effectively no hard faults were observed.
   WARM_STARTUP_TEMPERATURE = 1,
   // The startup type couldn't quite be classified as warm or cold, but rather
   // was somewhere in between.
   LUKEWARM_STARTUP_TEMPERATURE = 2,
   // This must be after all meaningful values.
   STARTUP_TEMPERATURE_COUNT,
   // Startup temperature wasn't yet determined.
   UNDETERMINED_STARTUP_TEMPERATURE
 };
 
 #if defined(OS_WIN)
 // Gets the hard fault count of the current process through |hard_fault_count|.
 // Returns true on success.
 bool GetHardFaultCountForCurrentProcess(uint32_t* hard_fault_count);
 #endif  // defined(OS_WIN)
 
 // 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.
 bool WasNonBrowserUIDisplayed();
 
-// Call this when displaying UI that might potentially delay the appearance
-// of the initial browser window on Chrome startup.
+// Call this when displaying UI that might potentially delay startup events.
 //
 // Note on usage: This function is idempotent and its overhead is low enough
 // in comparison with UI display that it's OK to call it on every
 // UI invocation regardless of whether the browser window has already
 // been displayed or not.
 void SetNonBrowserUIDisplayed();
 
 // Call this with the creation time of the startup (initial/main) process.
 void RecordStartupProcessCreationTime(const base::Time& time);
 
@@ skipping 12 matching lines @@
 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);
 
+// Logs the Startup.SameVersionStartupCount histogram. Relies on |pref_service|
+// to know information about the previous startups and store information for
+// future ones.
+void RecordStartupCount(PrefService* pref_service);
+
 // Call this with the time when the first browser window became visible.
 void RecordBrowserWindowDisplay(const base::TimeTicks& ticks);
 
 // Call this with the time delta that the browser spent opening its tabs.
 void RecordBrowserOpenTabsDelta(const base::TimeDelta& delta);
 
 // Call this with a renderer main entry time. The value provided for the first
 // call to this function is used to compute
 // Startup.LoadTime.BrowserMainToRendererMain. Further calls to this
 // function are ignored.
@@ skipping 21 matching lines @@
 base::TimeTicks MainEntryPointTicks();
 
 // Returns the startup type. This is only currently supported on the Windows
 // platform and will simply return UNCERTAIN_STARTUP_TYPE on other platforms.
 // This is only valid after a call to RecordBrowserMainMessageLoopStart().
 StartupTemperature GetStartupTemperature();
 
 }  // namespace startup_metric_utils
 
 #endif  // COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_UTILS_H_