dpwas: Don't add launch_query_params to start_url if they're already there

This CL updates how a web app's launch URL is computed given a
launch_query_params configuration. If the launch_query_params are
already present in the start_url then they are not appended a second
time.

Bug: 1142701
Change-Id: I394c8d96ee5e6a3776ed0c3555167b672b5e50b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2501107
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Glen Robertson <glenrob@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821638}

chrome/browser/web_applications/components/app_registrar.cc

@@ -152,6 +152,11 @@ GURL AppRegistrar::GetAppLaunchUrl(const AppId& app_id) const {
     return start_url.ReplaceComponents(replacements);
   }
 
+  if (start_url.query_piece().find(*launch_query_params) !=
+      base::StringPiece::npos) {
+    return start_url;
+  }
+
   std::string query_params = start_url.query() + "&" + *launch_query_params;
   replacements.SetQueryStr(query_params);
   return start_url.ReplaceComponents(replacements);

chrome/browser/web_applications/external_web_app_utils.cc

@@ -72,7 +72,12 @@ constexpr char kLaunchContainerTab[] = "tab";
 constexpr char kLaunchContainerWindow[] = "window";
 
 // kLaunchQueryParams is an optional string which specifies query parameters to
-// add to the start_url when launching the app.
+// add to the start_url when launching the app. If the provided params are a
+// substring of start_url's existing params then it will not be added a second
+// time.
+// Note that substring matches include "param=a" matching in "some_param=abc".
+// Extend the implementation in AppRegistrar::GetAppLaunchUrl() if this edge
+// case needs to be handled differently.
 constexpr char kLaunchQueryParams[] = "launch_query_params";
 
 // kLoadAndAwaitServiceWorkerRegistration is an optional bool that specifies