Add accessible image description feature to chrome://flags

This will allow people to enable it without needing to use a
command-line flag - especially on Chrome OS, where you can't
pass command-line flags without going into dev mode.

Bug: 905419
Change-Id: Idea85f6cdb88eb7c1c23a715af314255acc8bb5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1549854
Reviewed-by: Katie Dektar <[email protected]>
Commit-Queue: Dominic Mazzoni <[email protected]>
Cr-Commit-Position: refs/heads/master@{#647508}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 64725d2..d3262c47 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -252,6 +252,9 @@
 extern const char kEmbeddedExtensionOptionsName[];
 extern const char kEmbeddedExtensionOptionsDescription[];
 
+extern const char kEnableAccessibilityImageDescriptionsName[];
+extern const char kEnableAccessibilityImageDescriptionsDescription[];
+
 extern const char kEnableAccessibilityObjectModelName[];
 extern const char kEnableAccessibilityObjectModelDescription[];