android_webview: support building a stub WebView.

android_webview/system_webview_apk_tmpl.gni

Index: android_webview/system_webview_apk_tmpl.gni
diff --git a/android_webview/system_webview_apk_tmpl.gni b/android_webview/system_webview_apk_tmpl.gni
index 90bdc7f53f4aebac603afa6f0664bef5490ef3c6..d4e5b43ac8c4e5594bde5e583bff4737286e96ff 100644
--- a/android_webview/system_webview_apk_tmpl.gni
+++ b/android_webview/system_webview_apk_tmpl.gni
@@ -10,24 +10,33 @@ template("system_webview_apk_tmpl") {
   android_apk(target_name) {
     forward_variables_from(invoker, "*")
 
-    deps += [
-      "//android_webview:assets",
-      "//base:base_java",
-    ]
+    if (!defined(webview_stub_only)) {
+      webview_stub_only = false
+    }
+
+    deps += [ "//base:base_java" ]
 
     if (!defined(alternative_android_sdk_jar)) {
       alternative_android_sdk_jar = webview_framework_jar
     }
 
     shared_resources = true
-    shared_libraries = [ "//android_webview:libwebviewchromium" ]
     native_lib_version_rule = "//build/util:chrome_version_json"
     _native_lib_file =
         rebase_path("$root_gen_dir/CHROME_VERSION.json", root_out_dir)
     native_lib_version_arg = "@FileArg($_native_lib_file:full-quoted)"
-    if (build_apk_secondary_abi && android_64bit_target_cpu) {
-      secondary_abi_shared_libraries = [ "//android_webview:libwebviewchromium($android_secondary_abi_toolchain)" ]
+
+    if (webview_stub_only) {
+      unpackaged_shared_libraries = [ "libmonochrome.so" ]
+    } else {
+      deps += [ "//android_webview:assets" ]
+
+      shared_libraries = [ "//android_webview:libwebviewchromium" ]
+      if (build_apk_secondary_abi && android_64bit_target_cpu) {
+        secondary_abi_shared_libraries = [ "//android_webview:libwebviewchromium($android_secondary_abi_toolchain)" ]
+      }
     }
+
     aapt_locale_whitelist = locales
 
     if (!is_java_debug) {