[WebLayer] Use WebView sandboxed processes in all versions

This will hopefully improve performance in Android N (and earlier
versions). See bug for more details.

Bug: 1154056
Change-Id: I80f976761e24a14fa20f8d7d1de5f2058197ec58
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566339Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832530}

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

@@ -775,11 +775,12 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         String sandboxedServicesName = "org.chromium.weblayer.ChildProcessService$Sandboxed";
         boolean isExternalService = false;
         boolean loadedFromWebView = wasLoadedFromWebView(appContext);
-        if (loadedFromWebView && Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            // On O+ when loading from a WebView implementation, we can just use WebView's declared
-            // external services as our renderers, which means we benefit from the webview zygote
-            // process. We still need to use the client's privileged services, as only isolated
-            // services can be external.
+        if (loadedFromWebView && supportsBindingToWebViewService(appContext, implPackageName)) {
+            // When loading from a WebView implementation, use WebView's declared external services
+            // as our renderers. This means on O+ we benefit from the webview zygote process, and on
+            // other versions we ensure the client app doesn't slow down isolated process startup.
+            // We still need to use the client's privileged services, as only isolated services can
+            // be external.
             isExternalService = true;
             sandboxedServicesPackageName = implPackageName;
             sandboxedServicesName = null;
@@ -791,6 +792,29 @@ public final class WebLayerImpl extends IWebLayer.Stub {
                 ignoreVisibilityForImportance);
     }
 
+    private static boolean supportsBindingToWebViewService(Context context, String packageName) {
+        // BIND_EXTERNAL_SERVICE is not supported before N.
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
+            return false;
+        }
+
+        // Android N has issues with WebView with the non-system user.
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+            try {
+                PackageInfo packageInfo =
+                        context.getPackageManager().getPackageInfo(packageName, 0);
+                // Package may be disabled for non-system users.
+                if (!packageInfo.applicationInfo.enabled) {
+                    return false;
+                }
+            } catch (PackageManager.NameNotFoundException e) {
+                // Package may be uninstalled for non-system users.
+                return false;
+            }
+        }
+        return true;
+    }
+
     private static boolean wasLoadedFromWebView(Context appContext) {
         try {
             Bundle metaData = appContext.getPackageManager()