Add UMA for first app list paint on Windows.

chrome/browser/ui/app_list/app_list_service.cc

Index: chrome/browser/ui/app_list/app_list_service.cc
diff --git a/chrome/browser/ui/app_list/app_list_service.cc b/chrome/browser/ui/app_list/app_list_service.cc
index 5a5f9331883747652241c54aef9f6ea7f6732558..2576ab6865061aa52d9647132e7f91e1cbf5ca45 100644
--- a/chrome/browser/ui/app_list/app_list_service.cc
+++ b/chrome/browser/ui/app_list/app_list_service.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/ui/app_list/app_list_service.h"
 
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_registry_simple.h"
@@ -15,13 +17,53 @@
 
 namespace {
 
-base::TimeDelta GetTimeFromOriginalProcessStart(
-    const CommandLine& command_line) {
-  std::string start_time_string =
-      command_line.GetSwitchValueASCII(switches::kOriginalProcessStartTime);
-  int64 remote_start_time;
-  base::StringToInt64(start_time_string, &remote_start_time);
-  return base::Time::Now() - base::Time::FromInternalValue(remote_start_time);
+enum StartupType {
+  COLD_START,
+  WARM_START,
+  WARM_START_FAST,
+};
+
+base::Time GetOriginalProcessStartTime(const CommandLine& command_line) {
+  if (command_line.HasSwitch(switches::kOriginalProcessStartTime)) {
+    std::string start_time_string =
+        command_line.GetSwitchValueASCII(switches::kOriginalProcessStartTime);
+    int64 remote_start_time;
+    base::StringToInt64(start_time_string, &remote_start_time);
+    return base::Time::FromInternalValue(remote_start_time);
+  }
+
+// base::CurrentProcessInfo::CreationTime() is only defined on some
+// platforms.
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+    return base::CurrentProcessInfo::CreationTime();

[benwells, 2013/08/21 04:54:09]

Nit - indenting should be back two chars, this is an #if not an if().

[koz (OOO until 15th September), 2013/08/21 06:54:32]

Done.

+#endif
+  return base::Time();
+}
+
+StartupType GetStartupType(const CommandLine& command_line) {
+  // The presence of kOriginalProcessStartTime implies that another process
+  // has sent us its command line to handle, ie: we are already running.
+  if (command_line.HasSwitch(switches::kOriginalProcessStartTime)) {
+    return command_line.HasSwitch(switches::kFastStart) ?
+        WARM_START_FAST : WARM_START;
+  }
+  return COLD_START;
+}
+
+void RecordFirstPaintTiming(StartupType startup_type,
+                            const base::Time& start_time) {
+  base::TimeDelta elapsed = base::Time::Now() - start_time;
+  switch (startup_type) {
+  case WARM_START_FAST:

[benwells, 2013/08/21 04:54:09]

Nit: inside switch {} should be indented 2 more chars.
(http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Loops_...)

And below lines 89-99.

[koz (OOO until 15th September), 2013/08/21 06:54:32]

Done.

+    UMA_HISTOGRAM_LONG_TIMES("Startup.AppListFirstPaintWarmStartFast", elapsed);
+    break;
+  case WARM_START:
+    UMA_HISTOGRAM_LONG_TIMES("Startup.AppListFirstPaintWarmStart", elapsed);
+    break;
+  case COLD_START:
+    UMA_HISTOGRAM_LONG_TIMES("Startup.AppListFirstPaintColdStart", elapsed);
+    break;
+  }
 }
 
 }  // namespace
@@ -38,21 +80,24 @@ void AppListService::RegisterPrefs(PrefRegistrySimple* registry) {
 
 // static
 void AppListService::RecordShowTimings(const CommandLine& command_line) {
-  // The presence of kOriginalProcessStartTime implies that another process
-  // has sent us its command line to handle, ie: we are already running.
-  if (command_line.HasSwitch(switches::kOriginalProcessStartTime)) {
-    base::TimeDelta elapsed = GetTimeFromOriginalProcessStart(command_line);
-    if (command_line.HasSwitch(switches::kFastStart))
-      UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStartFast", elapsed);
-    else
-      UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStart", elapsed);
-  } else {
-    // base::CurrentProcessInfo::CreationTime() is only defined on some
-    // platforms.
-#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
-    UMA_HISTOGRAM_LONG_TIMES(
-        "Startup.ShowAppListColdStart",
-        base::Time::Now() - base::CurrentProcessInfo::CreationTime());
-#endif
+  base::Time start_time = GetOriginalProcessStartTime(command_line);
+  if (start_time.is_null())
+    return;
+
+  base::TimeDelta elapsed = base::Time::Now() - start_time;
+  StartupType startup = GetStartupType(command_line);
+  switch (startup) {
+  case COLD_START:

[benwells, 2013/08/21 04:54:09]

Super nit: use same ordering of enum here as in the previous switch.

[koz (OOO until 15th September), 2013/08/21 06:54:32]

Done.

+    UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListColdStart", elapsed);
+    break;
+  case WARM_START:
+    UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStart", elapsed);
+    break;
+  case WARM_START_FAST:
+    UMA_HISTOGRAM_LONG_TIMES("Startup.ShowAppListWarmStartFast", elapsed);
+    break;
   }
+
+  AppListService::Get()->SetAppListNextPaintCallback(
+      base::Bind(RecordFirstPaintTiming, startup, start_time));
 }