WebApp: Expose DesktopPWAsUnifiedInstall feature in chrome://flags.

Bug: 915043
Change-Id: I0d3b27271ca725d5188f5efcf709750f8b3cdfcf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1640521
Reviewed-by: Dominick Ng <[email protected]>
Commit-Queue: Alexey Baskakov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#665457}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index b133122..99f90cc 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -550,6 +550,11 @@
     "When on a site that passes PWA installation requirements show a button in "
     "the omnibox for installing it.";
 
+const char kDesktopPWAsUnifiedInstallName[] =
+    "Desktop PWAs Unified Installation.";
+const char kDesktopPWAsUnifiedInstallDescription[] =
+    "New unified installation process for Desktop PWAs.";
+
 const char kEnableSystemWebAppsName[] = "System Web Apps";
 const char kEnableSystemWebAppsDescription[] =
     "Experimental system for using the Desktop PWA framework for running System"