Add an experimental settings check into the getter for launchQRScanner.

ios/chrome/browser/app_startup_parameters.mm

Index: ios/chrome/browser/app_startup_parameters.mm
diff --git a/ios/chrome/browser/app_startup_parameters.mm b/ios/chrome/browser/app_startup_parameters.mm
index 8cac49b54a8016f139a496feba7ead51de1509b4..dd43c246b4a2e16654aa35aa159c35565f9f1c36 100644
--- a/ios/chrome/browser/app_startup_parameters.mm
+++ b/ios/chrome/browser/app_startup_parameters.mm
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
+#include "ios/chrome/browser/experimental_flags.h"
 #import "ios/chrome/browser/xcallback_parameters.h"
 #include "url/gurl.h"
 
@@ -19,7 +20,6 @@
 
 @synthesize launchVoiceSearch = _launchVoiceSearch;
 @synthesize launchInIncognito = _launchInIncognito;
-@synthesize launchQRScanner = _launchQRScanner;
 
 - (const GURL&)externalURL {
   return _externalURL;
@@ -54,4 +54,14 @@
                                     _xCallbackParameters.get()];
 }
 
+#pragma mark Property implementation.
+
+- (BOOL)launchQRScanner {
+  return _launchQRScanner && experimental_flags::IsQRCodeReaderEnabled();
+}
+
+- (void)setLaunchQRScanner:(BOOL)launch {
+  _launchQRScanner = launch;
+}
+
 @end