Create weblayer_browsertests target and one simple test.

This will be added to FYI bots in a followup cl.

Change-Id: I8ca2e3ce61e628cf6e342a8ab4fc604975c0d225
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1809897
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Auto-Submit: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697497}

diff --git a/BUILD.gn b/BUILD.gn
index 9a9ef733..ad0028b 100644
--- a/BUILD.gn
+++ b/BUILD.gn

@@ -196,6 +196,11 @@
     deps += [ "//weblayer/shell:weblayer_shell" ]
   }
 
+  # TODO: enable this on Android.
+  if (is_win || (is_linux && !is_chromeos)) {
+    deps += [ "//weblayer/test:weblayer_browsertests" ]
+  }
+
   if (!is_ios && !is_android) {
     deps += [
       "//components/cronet:cronet_tests",