Default-disable Incognito Mode for notouch builds.

Touchless Android mode doesn't support incognito by default, so set the
default availability to disabled.

Bug: 939732
Change-Id: Iae40962594559a4300e13a3165fbb5d15f6f2eb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1511829
Reviewed-by: Dominic Battré <[email protected]>
Commit-Queue: Michael Thiessen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#639518}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 5cd00bb..95fbb8e3 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -4886,6 +4886,10 @@
   if (use_udev) {
     deps += [ "//device/udev_linux" ]
   }
+
+  if (is_android && notouch_build) {
+    defines += [ "INCOGNITO_DEFAULT_DISABLED" ]
+  }
 }
 
 if (is_android) {