Support migrating multi-install Chrome to single-install.

chrome/installer/util/installation_validator.cc

Index: chrome/installer/util/installation_validator.cc
diff --git a/chrome/installer/util/installation_validator.cc b/chrome/installer/util/installation_validator.cc
index 5c0e25fc68be3b603a19347aef4607fc0db1e65e..0334ceb1c4c4d2fc2660d095df3e4b5de921d2be 100644
--- a/chrome/installer/util/installation_validator.cc
+++ b/chrome/installer/util/installation_validator.cc
@@ -11,13 +11,17 @@
 #include <string>
 
 #include "base/logging.h"
+#include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/version.h"
+#include "base/win/registry.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/google_update_constants.h"
 #include "chrome/installer/util/helper.h"
+#include "chrome/installer/util/install_util.h"
 #include "chrome/installer/util/installation_state.h"
+#include "chrome/installer/util/updating_app_registration_data.h"
 
 namespace installer {
 
@@ -552,6 +556,30 @@ bool InstallationValidator::ValidateInstallationTypeForState(
                  ProductBits::CHROME_SINGLE));
   }
 
+#if defined(GOOGLE_CHROME_BUILD)
+  if (!InstallUtil::IsChromeSxSProcess()) {
+    // Usage of the app launcher is tracked alongside Chrome.
+    const HKEY root_key = system_level ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
+    base::string16 launcher_key(
+        UpdatingAppRegistrationData(kAppLauncherGuid).GetVersionKey());
+    base::win::RegKey key(root_key, launcher_key.c_str(),
+                          KEY_QUERY_VALUE | KEY_WOW64_32KEY);
+    bool have_launcher =
+        key.Valid() && key.HasValue(google_update::kRegVersionField);
+
+    BrowserDistribution* chrome_dist =
+        BrowserDistribution::GetSpecificDistribution(
+            BrowserDistribution::CHROME_BROWSER);
+    if (!have_launcher) {
+      LOG_IF(ERROR, product_state) << "App launcher is not installed with "
+                                   << chrome_dist->GetDisplayName();
+    } else {
+      LOG_IF(ERROR, !product_state) << "App launcher is installed without "
+                                    << chrome_dist->GetDisplayName();
+    }
+  }
+#endif  // GOOGLE_CHROME_BUILD
+
   // Is Chrome Frame installed?
   product_state =
       machine_state.GetProductState(system_level,