[android webview] Future-proof ServiceWorker...shouldInterceptRequest

Guard the callback ServiceWorkerClientCompat.shouldInterceptRequest with
a feature flag to ensure that if we ever remove/replace that callback
from the support library in the future, existing WebView APKs won't call
into it.

Bug: 819595
Change-Id: Id9796f695cc9fd66caf5739efeb77dd02e215821
Reviewed-on: https://chromium-review.googlesource.com/998164Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Gustav Sennton <gsennton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549312}

android_webview/support_library/boundary_interfaces/src/org/chromium/support_lib_boundary/ServiceWorkerClientBoundaryInterface.java

@@ -10,6 +10,6 @@ import android.webkit.WebResourceResponse;
 /**
  * Boundary interface for ServiceWorkerClient.
  */
-public interface ServiceWorkerClientBoundaryInterface {
+public interface ServiceWorkerClientBoundaryInterface extends FeatureFlagHolderBoundaryInterface {
     WebResourceResponse shouldInterceptRequest(WebResourceRequest request);
 }

android_webview/support_library/boundary_interfaces/src/org/chromium/support_lib_boundary/util/BoundaryInterfaceReflectionUtil.java

@@ -71,4 +71,15 @@ public class BoundaryInterfaceReflectionUtil {
             }
         };
     }
+
+    /**
+     * Check whether a set of features {@param features} contains a certain feature {@param
+     * soughtFeature}.
+     */
+    public static boolean containsFeature(String[] features, String soughtFeature) {
+        for (String feature : features) {
+            if (feature.equals(soughtFeature)) return true;
+        }
+        return false;
+    }
 }

android_webview/support_library/java/src/org/chromium/support_lib_glue/SupportLibServiceWorkerClientAdapter.java

@@ -13,6 +13,8 @@ import org.chromium.android_webview.AwContentsClient.AwWebResourceRequest;
 import org.chromium.android_webview.AwServiceWorkerClient;
 import org.chromium.android_webview.AwWebResourceResponse;
 import org.chromium.support_lib_boundary.ServiceWorkerClientBoundaryInterface;
+import org.chromium.support_lib_boundary.util.BoundaryInterfaceReflectionUtil;
+import org.chromium.support_lib_boundary.util.Features;
 
 /**
  * Adapter between ServiceWorkerClientBoundaryInterface and AwServiceWorkerClient.
@@ -26,6 +28,11 @@ class SupportLibServiceWorkerClientAdapter extends AwServiceWorkerClient {
 
     @Override
     public AwWebResourceResponse shouldInterceptRequest(AwWebResourceRequest request) {
+        if (!BoundaryInterfaceReflectionUtil.containsFeature(mImpl.getSupportedFeatures(),
+                    Features.SERVICE_WORKER_SHOULD_INTERCEPT_REQUEST)) {
+            // If the shouldInterceptRequest callback isn't supported, return null;
+            return null;
+        }
         WebResourceResponse response =
                 mImpl.shouldInterceptRequest(new WebResourceRequestAdapter(request));
         return ServiceWorkerClientAdapter.fromWebResourceResponse(response);

android_webview/support_library/java/src/org/chromium/support_lib_glue/SupportLibWebViewChromiumFactory.java

@@ -43,7 +43,8 @@ class SupportLibWebViewChromiumFactory implements WebViewProviderFactoryBoundary
                     Features.SERVICE_WORKER_CACHE_MODE,
                     Features.SERVICE_WORKER_CONTENT_ACCESS,
                     Features.SERVICE_WORKER_FILE_ACCESS,
-                    Features.SERVICE_WORKER_BLOCK_NETWORK_LOADS
+                    Features.SERVICE_WORKER_BLOCK_NETWORK_LOADS,
+                    Features.SERVICE_WORKER_SHOULD_INTERCEPT_REQUEST
             };
     // clang-format on