[WebLayer] Enable WebLayer in split on stable

There have been no issues on beta, so enabling on stable.

    duplicated between dex files.

Bug: 1105096
Change-Id: I6f586a256c6304612f983e126258ce220b0d6f97
Binary-Size: Increase is unavoidable and comes from symbols being
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2572197
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842209}

android_webview/expectations/system_webview_bundle.AndroidManifest.expected

 <?xml version="1.0" ?>
 <manifest
+    android:isolatedSplits="true"
     package="com.android.webview"
     platformBuildVersionCode="30"
     platformBuildVersionName="11"

android_webview/expectations/trichrome_webview_bundle.AndroidManifest.expected

 <?xml version="1.0" ?>
 <manifest
+    android:isolatedSplits="true"
     package="com.android.webview"
     platformBuildVersionCode="30"
     platformBuildVersionName="11"

android_webview/system_webview_apk_tmpl.gni

@@ -59,6 +59,13 @@ template("system_webview_apk_or_module_tmpl") {
           "//android_webview:android_webview_no_weblayer_java",
           "//weblayer/browser/java:base_module_java",
         ]
+        if (defined(invoker.expected_android_manifest)) {
+          _bundle_target_gen_dir =
+              get_label_info(invoker.bundle_target, "target_gen_dir")
+          _bundle_name = get_label_info(invoker.bundle_target, "name")
+          extra_verification_manifest = "${_bundle_target_gen_dir}/${_bundle_name}__weblayer_bundle_module_manifest/AndroidManifest.xml"
+          extra_verification_manifest_dep = "${invoker.bundle_target}__weblayer_bundle_module__merge_manifests"
+        }
       } else {
         deps += [ "//android_webview:android_webview_java" ]
       }

weblayer/variables.gni

@@ -9,7 +9,7 @@ declare_args() {
   webview_includes_weblayer = true
 
   # Whether WebLayer will be included as a DFM.
-  weblayer_in_split = android_channel != "stable"
+  weblayer_in_split = true
 }
 
 weblayer_product_config_java_package = "org.chromium.weblayer_private"