[Switch Access] Add flag for setup guide

In preparation for the addition of a setup guide, add a flag to hide
the changes until launch.

Bug: None
Change-Id: I575714b064f2ee171ce907a9133692f7fad715ce
AX-Relnotes: n/a.
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2665413
Commit-Queue: Anastasia Helfinstein <[email protected]>
Reviewed-by: Josiah Krutz <[email protected]>
Reviewed-by: Katie Dektar <[email protected]>
Auto-Submit: Anastasia Helfinstein <[email protected]>
Cr-Commit-Position: refs/heads/master@{#850392}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 5825273..8afa4ab3 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2514,6 +2514,9 @@
 extern const char kSwitchAccessPointScanningName[];
 extern const char kSwitchAccessPointScanningDescription[];
 
+extern const char kExperimentalAccessibilitySwitchAccessSetupGuideName[];
+extern const char kExperimentalAccessibilitySwitchAccessSetupGuideDescription[];
+
 extern const char kMagnifierNewFocusFollowingName[];
 extern const char kMagnifierNewFocusFollowingDescription[];