Add a method to read the Omaha experiment_labels value.

chrome/installer/util/google_update_settings.cc

Index: chrome/installer/util/google_update_settings.cc
diff --git a/chrome/installer/util/google_update_settings.cc b/chrome/installer/util/google_update_settings.cc
index a53b61e0c6e9b9ac312e929331ff8883c397acd6..6657c73e60dda6089953f01f96320cd0c14ffc7d 100644
--- a/chrome/installer/util/google_update_settings.cc
+++ b/chrome/installer/util/google_update_settings.cc
@@ -668,3 +668,23 @@ bool GoogleUpdateSettings::SetExperimentLabels(
 
   return success;
 }
+
+bool GoogleUpdateSettings::ReadExperimentLabels(
+    bool system_install,
+    string16* experiment_labels) {
+  HKEY reg_root = system_install ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
+
+  // If this distribution does not set the experiment labels, don't bother
+  // reading.
+  bool success = false;
+  BrowserDistribution* dist = BrowserDistribution::GetDistribution();
+  if (dist->ShouldSetExperimentLabels()) {
+    string16 client_state_path(
+        system_install ? dist->GetStateMediumKey() : dist->GetStateKey());
+    RegKey client_state(reg_root, client_state_path.c_str(), KEY_READ);

[grt (UTC plus 2), 2013/01/09 18:49:51]

KEY_READ -> KEY_QUERY_VALUE

[SteveT, 2013/01/09 19:36:10]

Done. Care to explain the difference, though?

[grt (UTC plus 2), 2013/01/10 02:58:51]

I think it's good practice to request least privileges. QUERY_VALUE is all
that's needed for the next line, so it's all that should be requested.

[SteveT, 2013/01/10 15:05:51]

What's the difference between the two?

Feel free to point me to a link if you don't feel like writing a big blurb here
:)  I'm just curious for the future.

[grt (UTC plus 2), 2013/01/10 15:10:19]

http://msdn.microsoft.com/library/windows/desktop/ms724878.aspx

+    success = client_state.ReadValue(google_update::kExperimentLabels,
+                                     experiment_labels) == ERROR_SUCCESS;
+  }
+
+  return success;
+}