Clean Read/SetExperimentLabels to remove check for Chrome build.

chrome/browser/metrics/variations/chrome_variations_service_client.cc

Index: chrome/browser/metrics/variations/chrome_variations_service_client.cc
diff --git a/chrome/browser/metrics/variations/chrome_variations_service_client.cc b/chrome/browser/metrics/variations/chrome_variations_service_client.cc
index e4bfb1e89c3aedc9b374a40c625959247eec29a5..391f5199432dd5e0fb65707ce2b324c265075fc1 100644
--- a/chrome/browser/metrics/variations/chrome_variations_service_client.cc
+++ b/chrome/browser/metrics/variations/chrome_variations_service_client.cc
@@ -17,6 +17,7 @@
 #include "base/strings/string16.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/installer/util/google_update_settings.h"
+#include "chrome/installer/util/install_modes.h"

[grt (UTC plus 2), 2017/06/02 13:29:28]

installer/util -> install_static
and move into proper sorted position

[nikunjb, 2017/06/02 21:31:43]

Acknowledged. (No longer needed)

 #include "chrome/installer/util/install_util.h"
 #include "components/variations/experiment_labels.h"
 #endif
@@ -52,7 +53,10 @@ base::Version GetVersionForSimulation() {
 // labels (M57-M58 timeframe).

[Alexei Svitkine (slow), 2017/06/02 15:11:41]

We have a TODO here to remove this code entirely. Instead of making further
changes, can we simply delete this code?

(The context is we used to integrate with Google Update to plumb some
experiments through to it. When we removed this support last year, we left this
code in to clean up existing registry keys. By this point, they've probably all
been cleaned up and we could just delete this code.)

[grt (UTC plus 2), 2017/06/02 15:16:52]

SGTM to delete the code in metrics. We're keeping the code in installer/util for
use in the upcoming retention experiment.

 void ClearGoogleUpdateRegistryLabels() {
   base::ThreadRestrictions::AssertIOAllowed();
-
+  // There is nothing to do if this brand does not support integration with
+  // Google Update.
+  if (!install_static::kUseGoogleUpdateIntegration)
+    return;
   // Note that all registry operations are done here on the UI thread as there
   // are no threading restrictions on them.
   const bool is_system_install = !InstallUtil::IsPerUserInstall();