[WebApps] Flag enabling a Minimal-UI display mode for installed PWAs.

As Minimal-UI is a UX change it is considered useful to put it behind
a flag to gather feedback from the team before enabling it for a wider
audience.

Bug: 604390
Change-Id: I24f4588b357249b06f400e05e53c0805518cecb1
Reviewed-on: https://chromium-review.googlesource.com/609570
Commit-Queue: Piotr Swigon <[email protected]>
Reviewed-by: Dominick Ng <[email protected]>
Cr-Commit-Position: refs/heads/master@{#493637}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index f1ad12f..5d33e79 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3339,6 +3339,12 @@
      FEATURE_VALUE_TYPE(features::kVoiceSearchOnLocalNtp)},
 #endif  // !defined(OS_ANDROID)
 
+#if defined(OS_ANDROID)
+    {"pwa-minimal-ui", flag_descriptions::kPwaMinimalUiName,
+     flag_descriptions::kPwaMinimalUiDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(chrome::android::kPwaMinimalUi)},
+#endif  // OS_ANDROID
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms/enums.xml. See note in
     // enums.xml and don't forget to run AboutFlagsHistogramTest unit test.