Report Windows build and patch number in the component updater checks.

components/update_client/utils_win.cc

+// Copyright 2016 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.
+
+#include "components/update_client/utils_win.h"
+
+#include <windows.h>
+
+#include "base/strings/string16.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+#include "base/sys_info.h"
+#include "base/win/registry.h"
+
+namespace update_client {
+
+namespace {
+
+constexpr wchar_t kRegKeyWindowsNTCurrentVersion[] =
+    L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion";
+
+constexpr wchar_t kRegValCurrentBuild[] = L"CurrentBuild";
+constexpr wchar_t kRegValCurrentBuildNumber[] = L"CurrentBuildNumber";
+constexpr wchar_t kRegValUBR[] = L"UBR";
+
+}  // namespace
+
+// This function implements a best-effort algorithm to return the
+// Windows build and patch numbers as part of the Windows OS version.
+// The build and patch numbers are read from
+// HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion and they are
+// replicated under the corresponding Wow6432 hive for the 32-bit programs to
+// read.
+std::string GetWindowsOSVersion() {
+  int32_t major = 0;
+  int32_t minor = 0;
+  int32_t bugfix = 0;
+  base::SysInfo::OperatingSystemVersionNumbers(&major, &minor, &bugfix);
+
+  base::win::RegKey key;
+  if (key.Open(HKEY_LOCAL_MACHINE, kRegKeyWindowsNTCurrentVersion,
+               KEY_QUERY_VALUE) != ERROR_SUCCESS) {
+    return base::StringPrintf("%d.%d.%d.%d", major, minor, bugfix, 0);
+  }
+
+  // Try "CurrentBuild", then fallback to "CurrentBuildNumber". Convert the

[grt (UTC plus 2), 2016/11/15 10:25:49]

does this differ from the build # obtained by GetVersionEx?

[Sorin Jianu, 2016/11/15 19:06:52]

The same value is retrieved in both cases.

+  // string value to an integral type for validation.
+  base::string16 build_str;
+  if (key.ReadValue(kRegValCurrentBuild, &build_str) != ERROR_SUCCESS)
+    key.ReadValue(kRegValCurrentBuildNumber, &build_str);
+  unsigned int build_number = 0;
+  base::StringToUint(build_str, &build_number);
+
+  DWORD patch = 0;
+  key.ReadValueDW(kRegValUBR, &patch);

[grt (UTC plus 2), 2016/11/15 10:25:49]

i like having this value available. i like it so much that i think it's better
to read it in OSInfo::OSInfo and cache it in the global instance so that it's
easily available throughout the product. wdyt?

[Sorin Jianu, 2016/11/15 19:06:52]

It makes sense. I am not quite sure what UBR represents, it seems it is some
kind of patch number, so to avoid confusion I might implemented as "UBR" until
someone figures out what it is.

+
+  return base::StringPrintf("%d.%d.%u.%lu", major, minor, build_number, patch);

[grt (UTC plus 2), 2016/11/15 10:25:49]

wdyt of putting UBR in the string returned by
base::SysInfo::OperatingSystemVersion (which already contains the build number)
and using that for all platforms? this will have the value appear in a variety
of places where it may be useful, such as feedback reports, bugs filed from
within Chrome, etc (see a somewhat old list here
https://docs.google.com/a/google.com/spreadsheets/d/1XVa79TbhQKfIgQXXcHvkB7U0...).

[Sorin Jianu, 2016/11/15 19:06:52]

I thought about it but I am not sure what is going to break.

+}
+
+}  // namespace update_client