Add histograms to compare GetVersionEx() with VerQueryValue() of kernel32

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 2b1664fa2fc4bd83567be2e1d6eeec7f6291b47c..2f98903a6ded1c9aced6ce8a7d5556fbcd5d35f9 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -131,6 +131,7 @@
 #include <shellapi.h>
 
 #include "base/memory/memory_pressure_monitor_win.h"
+#include "base/win/windows_version.h"
 #include "content/common/sandbox_win.h"
 #include "net/base/winsock_init.h"
 #include "ui/base/l10n/l10n_util_win.h"
@@ -1333,6 +1334,13 @@ int BrowserMainLoop::BrowserThreadsStarted() {
 
 #endif  // !defined(OS_IOS)
 
+#if defined(OS_WIN)
+  BrowserThread::PostDelayedTask(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&BrowserMainLoop::RecordWindowsVersionInformation),
+      base::TimeDelta::FromSeconds(3));
+#endif
+
   return result_code_;
 }
 
@@ -1341,6 +1349,21 @@ bool BrowserMainLoop::UsingInProcessGpu() const {
          parsed_command_line_.HasSwitch(switches::kInProcessGPU);
 }
 
+#if defined(OS_WIN)
+void BrowserMainLoop::RecordWindowsVersionInformation() {

[ncarter (slow), 2016/03/10 18:19:27]

Does this instrumentation belong in content or chrome?

Did you consider putting this in chrome_browser_main_win.cc instead?

[ncarter (slow), 2016/03/10 18:21:40]

Also, perhaps chrome_browser_main_extra_parts_metrics.cc is an even better fit?

[scottmg, 2016/03/10 23:51:40]

Done.

+  UMA_HISTOGRAM_ENUMERATION("Windows.GetVersionExVersion",
+                            base::win::OSInfo::GetInstance()->version(),
+                            base::win::VERSION_WIN_LAST);

[grt (UTC plus 2), 2016/03/10 19:43:44]

please add a doc comment to enum Version in windows_version.h stating that it's
used for a histogram and values must not be reordered. while you're at it, add
an explicit " = N" value to each element so that this is crystal clear.

[scottmg, 2016/03/10 23:51:40]

Done.

+  UMA_HISTOGRAM_ENUMERATION("Windows.Kernel32Version",
+                            base::win::OSInfo::GetInstance()->Kernel32Version(),
+                            base::win::VERSION_WIN_LAST);
+  UMA_HISTOGRAM_BOOLEAN(
+      "Windows.InCompatibilityMode",
+      base::win::OSInfo::GetInstance()->version() !=
+          base::win::OSInfo::GetInstance()->Kernel32Version());
+}
+#endif  // OS_WIN
+
 bool BrowserMainLoop::InitializeToolkit() {
   TRACE_EVENT0("startup", "BrowserMainLoop::InitializeToolkit");
   TRACK_SCOPED_REGION("Startup", "BrowserMainLoop::InitializeToolkit");