[WebLayer] Load resources correctly for standalone WebView APK

This fixes resources loading, and allows WebLayer to work with the
standalone WebView APK, which previously would crash with a
Resources$NotFoundException exception.

Adds a run_weblayer_shell_webview build target for testing with
standalone WebView.

Change-Id: If1063efdfbf462ccf36bc54f796d3b934a456274
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1854204Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706086}

weblayer/browser/java/BUILD.gn

@@ -5,6 +5,11 @@
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
 
+android_resources("weblayer_resources") {
+  resource_dirs = []
+  custom_package = "org.chromium.weblayer_private"
+}
+
 android_library("java") {
   java_files = [
     "org/chromium/weblayer_private/BrowserControllerImpl.java",
@@ -25,6 +30,7 @@ android_library("java") {
 
   deps = [
     ":client_java",
+    ":weblayer_resources",
     "//base:base_java",
     "//base:jni_java",
     "//content/public/android:content_java",

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -52,8 +52,12 @@ public final class WebLayerImpl extends IWebLayer.Stub {
     }
 
     @Override
-    public void initAndLoadAsync(
-            IObjectWrapper webLayerContextWrapper, IObjectWrapper loadedCallbackWrapper) {
+    public void initAndLoadAsync(IObjectWrapper webLayerContextWrapper,
+            IObjectWrapper loadedCallbackWrapper, int resourcesPackageId) {
+        // TODO: The call to onResourcesLoaded() can be slow, we may need to parallelize this with
+        // other expensive startup tasks.
+        R.onResourcesLoaded(resourcesPackageId);
+
         Context context = ObjectWrapper.unwrap(webLayerContextWrapper, Context.class);
         ContextUtils.initApplicationContext(context);
         ResourceBundle.setNoAvailableLocalePaks();

weblayer/browser/java/org/chromium/weblayer_private/aidl/IWebLayer.aidl

@@ -16,7 +16,8 @@ interface IWebLayer {
   // when load completes. |webLayerContext| is a Context that refers to the
   // WebLayer implementation.
   void initAndLoadAsync(in IObjectWrapper webLayerContext,
-                        in IObjectWrapper loadedCallback) = 1;
+                        in IObjectWrapper loadedCallback,
+                        int resourcesPackageId) = 1;
 
   // Blocks until loading has completed.
   void loadSync() = 2;

weblayer/public/java/org/chromium/weblayer/WebLayer.java

@@ -10,7 +10,6 @@ import android.content.ContextWrapper;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
-import android.content.res.Resources;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.os.RemoteException;
@@ -48,26 +47,9 @@ public final class WebLayer {
      * Loads the WebLayer implementation and returns the IWebLayer. This does *not* trigger the
      * implementation to start.
      */
-    private static IWebLayer connectToWebLayerImplementation(Context application)
+    private static IWebLayer connectToWebLayerImplementation(Context remoteContext)
             throws UnsupportedVersionException {
         try {
-            // TODO: Make asset loading work on L, where WebViewDelegate doesn't exist.
-            // WebViewDelegate.addWebViewAssetPath() accesses the currently loaded package info from
-            // WebViewFactory, so we have to fake it.
-            PackageInfo implPackageInfo = application.getPackageManager().getPackageInfo(
-                    getImplPackageName(application), PackageManager.GET_META_DATA);
-            Field packageInfo = WebViewFactory.class.getDeclaredField("sPackageInfo");
-            packageInfo.setAccessible(true);
-            packageInfo.set(null, implPackageInfo);
-
-            // TODO(torne): Figure out how to load assets for production.
-            // Load assets using the WebViewDelegate.
-            Constructor constructor = WebViewDelegate.class.getDeclaredConstructor();
-            constructor.setAccessible(true);
-            WebViewDelegate delegate = (WebViewDelegate) constructor.newInstance();
-            delegate.addWebViewAssetPath(application);
-
-            Context remoteContext = createRemoteContext(application);
             Class webLayerClass = remoteContext.getClassLoader().loadClass(
                     "org.chromium.weblayer_private.WebLayerImpl");
 
@@ -86,6 +68,35 @@ public final class WebLayer {
         }
     }
 
+    /**
+     * Loads assets for WebLayer and returns the package ID to use when calling
+     * R.onResourcesLoaded().
+     */
+    private static int loadAssets(Context appContext, Context remoteContext) {
+        WebViewDelegate delegate;
+        PackageInfo implPackageInfo;
+        try {
+            // TODO: Make asset loading work on L, where WebViewDelegate doesn't exist.
+            // WebViewDelegate.addWebViewAssetPath() accesses the currently loaded package info from
+            // WebViewFactory, so we have to fake it.
+            implPackageInfo = appContext.getPackageManager().getPackageInfo(
+                    getImplPackageName(appContext), PackageManager.GET_META_DATA);
+            Field packageInfo = WebViewFactory.class.getDeclaredField("sPackageInfo");
+            packageInfo.setAccessible(true);
+            packageInfo.set(null, implPackageInfo);
+
+            // TODO(torne): Figure out how to load assets for production.
+            // Load assets using the WebViewDelegate.
+            Constructor constructor = WebViewDelegate.class.getDeclaredConstructor();
+            constructor.setAccessible(true);
+            delegate = (WebViewDelegate) constructor.newInstance();
+        } catch (Exception e) {
+            throw new AndroidRuntimeException(e);
+        }
+        delegate.addWebViewAssetPath(appContext);
+        return delegate.getPackageId(appContext.getResources(), implPackageInfo.packageName);
+    }
+
     /**
      * Asynchronously creates and initializes WebLayer. Calling this more than once returns the same
      * object.
@@ -97,9 +108,10 @@ public final class WebLayer {
     public static ListenableFuture<WebLayer> create(Context appContext)
             throws UnsupportedVersionException {
         if (sFuture == null) {
-            IWebLayer iWebLayer = connectToWebLayerImplementation(
-                    appContext.getApplicationContext());
-            sFuture = new WebLayerLoadFuture(iWebLayer, appContext);
+            Context remoteContext = createRemoteContext(appContext.getApplicationContext());
+            IWebLayer iWebLayer = connectToWebLayerImplementation(remoteContext);
+            int resourcesPackageId = loadAssets(appContext, remoteContext);
+            sFuture = new WebLayerLoadFuture(iWebLayer, remoteContext, resourcesPackageId);
         }
         return sFuture;
     }
@@ -110,7 +122,7 @@ public final class WebLayer {
     private static final class WebLayerLoadFuture extends ListenableFuture<WebLayer> {
         private final IWebLayer mIWebLayer;
 
-        WebLayerLoadFuture(IWebLayer iWebLayer, Context application) {
+        WebLayerLoadFuture(IWebLayer iWebLayer, Context remoteContext, int resourcesPackageId) {
             mIWebLayer = iWebLayer;
             ValueCallback<Boolean> loadCallback = new ValueCallback<Boolean>() {
                 @Override
@@ -121,8 +133,8 @@ public final class WebLayer {
                 }
             };
             try {
-                iWebLayer.initAndLoadAsync(ObjectWrapper.wrap(createRemoteContext(application)),
-                        ObjectWrapper.wrap(loadCallback));
+                iWebLayer.initAndLoadAsync(ObjectWrapper.wrap(remoteContext),
+                        ObjectWrapper.wrap(loadCallback), resourcesPackageId);
             } catch (RemoteException e) {
                 throw new APICallException(e);
             }
@@ -219,11 +231,6 @@ public final class WebLayer {
                 return wrapContext(getBaseContext().getApplicationContext(), remoteContext);
             }
 
-            @Override
-            public Resources getResources() {
-                return remoteContext.getResources();
-            }
-
             @Override
             public ClassLoader getClassLoader() {
                 return remoteContext.getClassLoader();

weblayer/shell/android/BUILD.gn

@@ -129,6 +129,23 @@ if (public_android_sdk) {
       "//chrome/android:trichrome_library_apk",
     ]
   }
+
+  generate_wrapper("run_weblayer_shell_webview") {
+    testonly = true
+    wrapper_script = "$root_out_dir/bin/run_weblayer_shell_webview"
+    executable = "//weblayer/tools/run_weblayer_shell.py"
+    executable_args = [
+      "--shell-apk-path",
+      "@WrappedPath(apks/WebLayerShellWebView.apk)",
+      "--support-apk-path",
+      "@WrappedPath(apks/SystemWebView.apk)",
+    ]
+
+    deps = [
+      ":weblayer_shell_webview_apk",
+      "//android_webview:system_webview_apk",
+    ]
+  }
 }
 
 demo_apk_manifest = "$target_gen_dir/demo_apk_manifest/AndroidManifest.xml"
@@ -230,6 +247,7 @@ android_apk("weblayer_support_apk") {
   min_sdk_version = 21
   target_sdk_version = 28
   android_manifest_dep = ":weblayer_support_manifest"
+  shared_resources = true
 
   native_lib_version_rule = "//build/util:chrome_version_json"
   _native_lib_file =