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..59ee0398e97e47c2350817b7e8566a08d9058338 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"
@@ -695,6 +696,20 @@ void BrowserMainLoop::PostMainMessageLoopStart() {
       skia::SkiaMemoryDumpProvider::GetInstance(), "Skia", nullptr);
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       sql::SqlMemoryDumpProvider::GetInstance(), "Sql", nullptr);
+
+#if defined(OS_WIN)
+  UMA_HISTOGRAM_ENUMERATION("Windows.GetVersionExVersion",
+                            base::win::OSInfo::GetInstance()->version(),
+                            base::win::VERSION_WIN_LAST);
+  UMA_HISTOGRAM_ENUMERATION(
+      "Windows.Kernel32Version",
+      base::win::OSInfo::GetInstance()->kernel32_version(),

[Will Harris, 2016/03/09 23:02:50]

given this call can loadlibrary, should it be moved off the hotpath for startup
e.g. into a posttaskwithdelay?

[scottmg, 2016/03/10 00:41:31]

Done. (It wouldn't have done IO here before, but now it will since
Kernel32Version() retrieves on demand)

+      base::win::VERSION_WIN_LAST);
+  UMA_HISTOGRAM_BOOLEAN(
+      "Windows.InCompatibilityMode",
+      base::win::OSInfo::GetInstance()->version() !=
+          base::win::OSInfo::GetInstance()->kernel32_version());
+#endif  // OS_WIN
 }
 
 int BrowserMainLoop::PreCreateThreads() {