Enable QR scanner to be opened at startup.

Also: adds command IDC to show QR scanner.

BUG=none

Review-Url: https://codereview.chromium.org/2144903003
Cr-Commit-Position: refs/heads/master@{#406273}
diff --git a/ios/chrome/browser/about_flags.mm b/ios/chrome/browser/about_flags.mm
index 79a4628..2f114dd 100644
--- a/ios/chrome/browser/about_flags.mm
+++ b/ios/chrome/browser/about_flags.mm
@@ -206,6 +206,11 @@
                                     web::BuildUserAgentFromProduct(product));
   }
 
+  // Populate command line flags from QRScanner.
+  if ([defaults boolForKey:@"EnableQRCodeReader"]) {
+    command_line->AppendSwitch(switches::kEnableQRScanner);
+  }
+
   // Freeform commandline flags.  These are added last, so that any flags added
   // earlier in this function take precedence.
   if ([defaults boolForKey:@"EnableFreeformCommandLineFlags"]) {