Display Cutout: Add feature

Add a 'DisplayCutoutAPI' feature that will switch on the
viewport-fit code (and the in future css safe-area-* code).

BUG=838400

Change-Id: I6a8f95b1a4cef33349787779ff2993a0f0453bff
Reviewed-on: https://chromium-review.googlesource.com/1043078
Commit-Queue: Becca Hughes <[email protected]>
Reviewed-by: Pavel Feldman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#556224}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index a37dc74..56ec86f 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2014,6 +2014,13 @@
 
 #endif  // defined(TOOLKIT_VIEWS) || defined(OS_ANDROID)
 
+#if defined(OS_ANDROID)
+
+extern const char kDisplayCutoutAPIName[];
+extern const char kDisplayCutoutAPIDescription[];
+
+#endif  // defined(OS_ANDROID)
+
 // ============================================================================
 // Don't just add flags to the end, put them in the right section in
 // alphabetical order. See top instructions for more.