Web restrictions component only.

components/web_restrictions/java/src/org/chromium/components/webrestrictions/ContentResolverWebRestrictionsProvider.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.components.webrestrictions;
+
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.database.ContentObserver;
+import android.database.Cursor;
+import android.net.Uri;
+import android.text.TextUtils;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+/**
+ * This class acts as an interface that talks to the content provider which actually implements the
+ * web restriction provider.
+ */
+@JNINamespace("web_restrictions")
+public class ContentResolverWebRestrictionsProvider {
+    private final Uri mQueryUri;
+    private final Uri mRequestUri;
+    private final ContentObserver mContentObserver;
+    private ContentResolver mContentResolver;
+
+    /**
+     * Start the web restriction provider and setup the content resolver.
+     */
+    private ContentResolverWebRestrictionsProvider(String authority, final long nativeProvider) {
+        assert !TextUtils.isEmpty(authority);
+        Uri baseUri = new Uri.Builder().scheme("content").authority(authority).build();
+        mQueryUri = Uri.withAppendedPath(baseUri, "authorized");
+        mRequestUri = Uri.withAppendedPath(baseUri, "requested");
+        mContentResolver = ContextUtils.getApplicationContext().getContentResolver();
+        mContentObserver = new ContentObserver(null) {
+            @Override
+            public void onChange(boolean selfChange) {
+                onChange(selfChange, null);
+            }
+
+            @Override
+            public void onChange(boolean selfChange, Uri uri) {
+                nativeNotifyWebRestrictionsChanged(nativeProvider);
+            }
+        };
+        mContentResolver.registerContentObserver(baseUri, true, mContentObserver);
+    }
+
+    /**
+     * Simple helper method to expose the constructor over JNI.
+     */
+    @CalledByNative
+    private static ContentResolverWebRestrictionsProvider create(
+            String authority, long nativeProvider) {
+        return new ContentResolverWebRestrictionsProvider(authority, nativeProvider);
+    }
+
+    /**
+     * @return whether the web restriction provider supports requesting access for a blocked url.
+     */
+    @CalledByNative
+    private boolean supportsRequest() {
+        return mContentResolver.getType(mRequestUri) != null;
+    }
+
+    /**
+     * Called when the ContentResolverWebRestrictionsProvider is about to be destroyed.
+     */
+    @CalledByNative
+    private void onDestroy() {
+        mContentResolver.unregisterContentObserver(mContentObserver);
+        // Ensure we don't use it any more.
+        mContentResolver = null;
+    }
+
+    /**
+     * Whether we can proceed with loading the {@code url}.
+     * In case the url is not to be loaded, the web restriction provider can return an optional
+     * error page to show instead.
+     */
+    @CalledByNative
+    private void shouldProceed(final long nativeCallback, final String url) {
+        String select = String.format("url = '%s'", url);
+        Cursor result = mContentResolver.query(mQueryUri, null, select, null, null);
+        boolean shouldProceed = result == null || result.getInt(0) > 0;
+        String errorPage = shouldProceed ? null : result.getString(1);
+        nativeShouldProceed(nativeCallback, shouldProceed, errorPage);
+    }
+
+    /**
+     * Request permission to load the {@code url}.
+     * The web restriction provider returns a {@code boolean} variable indicating whether it was
+     * able to forward the request to the appropriate authority who can approve it.
+     */
+    @CalledByNative
+    private void requestPermission(final long nativeCallback, final String url) {
+        ContentValues values = new ContentValues(1);
+        values.put("url", url);
+        boolean requestSuccess = mContentResolver.insert(mRequestUri, values) != null;
+        nativeRequestSuccess(nativeCallback, requestSuccess);
+    }
+
+    private static native void nativeShouldProceed(
+            long ptrSelfDeletingCallback, boolean shouldProceed, String errorPage);
+
+    private static native void nativeRequestSuccess(
+            long ptrSelfDeletingCallback, boolean requestSuccess);
+
+    private static native void nativeNotifyWebRestrictionsChanged(long ptrProvider);
+}