Make the URL for the JavaScript based screen-reader used by WebView configurable.

The URl from which to inject a screen-reader for WebView accessiblity support should be
configurable because: 1) The accessibility engineering team should be able to point
devices to a staging build of the screen-reader; 2) We would like to be able to change
this URL via the Google services mechanism.

bug:5718543

Change-Id: I3d4d343f1c93e0e0173f04b2912949fe8a3566b9

core/java/android/provider/Settings.java

@@ -2779,10 +2779,10 @@ public final class Settings {
         public static final String ACCESSIBILITY_SPEAK_PASSWORD = "speak_password";
 
         /**
-         * If injection of accessibility enhancing JavaScript scripts
+         * If injection of accessibility enhancing JavaScript screen-reader
          * is enabled.
          * <p>
-         *   Note: Accessibility injecting scripts are served by the
+         *   Note: The JavaScript based screen-reader is served by the
          *   Google infrastructure and enable users with disabilities to
          *   efficiantly navigate in and explore web content.
          * </p>
@@ -2794,6 +2794,22 @@ public final class Settings {
         public static final String ACCESSIBILITY_SCRIPT_INJECTION =
             "accessibility_script_injection";
 
+        /**
+         * The URL for the injected JavaScript based screen-reader used
+         * for providing accessiblity of content in WebView.
+         * <p>
+         *   Note: The JavaScript based screen-reader is served by the
+         *   Google infrastructure and enable users with disabilities to
+         *   efficiently navigate in and explore web content.
+         * </p>
+         * <p>
+         *   This property represents a string value.
+         * </p>
+         * @hide
+         */
+        public static final String ACCESSIBILITY_SCREEN_READER_URL =
+            "accessibility_script_injection_url";
+
         /**
          * Key bindings for navigation in built-in accessibility support for web content.
          * <p>

core/java/android/webkit/WebView.java

@@ -59,6 +59,7 @@ import android.os.Message;
 import android.os.StrictMode;
 import android.provider.Settings;
 import android.speech.tts.TextToSpeech;
+import android.text.TextUtils;
 import android.util.AttributeSet;
 import android.util.EventLog;
 import android.util.Log;
@@ -849,13 +850,12 @@ public class WebView extends AbsoluteLayout
     // the alias via which accessibility JavaScript interface is exposed
     private static final String ALIAS_ACCESSIBILITY_JS_INTERFACE = "accessibility";
 
-    // JavaScript to inject the script chooser which will
-    // pick the right script for the current URL
-    private static final String ACCESSIBILITY_SCRIPT_CHOOSER_JAVASCRIPT =
+    // Template for JavaScript that injects a screen-reader.
+    private static final String ACCESSIBILITY_SCREEN_READER_JAVASCRIPT_TEMPLATE =
         "javascript:(function() {" +
         "    var chooser = document.createElement('script');" +
         "    chooser.type = 'text/javascript';" +
-        "    chooser.src = 'https://ssl.gstatic.com/accessibility/javascript/android/AndroidScriptChooser.user.js';" +
+        "    chooser.src = '%1s';" +
         "    document.getElementsByTagName('head')[0].appendChild(chooser);" +
         "  })();";
 
@@ -3818,7 +3818,7 @@ public class WebView extends AbsoluteLayout
             if (onDeviceScriptInjectionEnabled) {
                 ensureAccessibilityScriptInjectorInstance(false);
                 // neither script injected nor script injection opted out => we inject
-                loadUrl(ACCESSIBILITY_SCRIPT_CHOOSER_JAVASCRIPT);
+                loadUrl(getScreenReaderInjectingJs());
                 // TODO: Set this flag after successfull script injection. Maybe upon injection
                 // the chooser should update the meta tag and we check it to declare success
                 mAccessibilityScriptInjected = true;
@@ -3832,7 +3832,7 @@ public class WebView extends AbsoluteLayout
         } else if (axsParameterValue == ACCESSIBILITY_SCRIPT_INJECTION_PROVIDED) {
             ensureAccessibilityScriptInjectorInstance(false);
             // the URL provides accessibility but we still need to add our generic script
-            loadUrl(ACCESSIBILITY_SCRIPT_CHOOSER_JAVASCRIPT);
+            loadUrl(getScreenReaderInjectingJs());
         } else {
             Log.e(LOGTAG, "Unknown URL value for the \"axs\" URL parameter: " + axsParameterValue);
         }
@@ -3853,6 +3853,17 @@ public class WebView extends AbsoluteLayout
         }
     }
 
+    /**
+     * Gets JavaScript that injects a screen-reader.
+     *
+     * @return The JavaScript snippet.
+     */
+    private String getScreenReaderInjectingJs() {
+        String screenReaderUrl = Settings.Secure.getString(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_SCREEN_READER_URL);
+        return String.format(ACCESSIBILITY_SCREEN_READER_JAVASCRIPT_TEMPLATE, screenReaderUrl);
+    }
+
     /**
      * Gets the "axs" URL parameter value.
      *

packages/SettingsProvider/res/values/defaults.xml

@@ -115,6 +115,11 @@
             0x200000038=0x03000701:0x03010701:0x03020701;
     </string>
 
+    <!-- Default for Settings.Secure.ACCESSIBILITY_SCRIPT_INJECTION_URL -->
+    <string name="def_accessibility_screen_reader_url" translatable="false">
+        https://ssl.gstatic.com/accessibility/javascript/android/AndroidScriptChooser.user.js
+    </string>
+
     <!-- Default for Settings.Secure.TOUCH_EXPLORATION_ENABLED -->
     <bool name="def_touch_exploration_enabled">false</bool>
 

packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java

@@ -63,7 +63,7 @@ public class DatabaseHelper extends SQLiteOpenHelper {
     // database gets upgraded properly. At a minimum, please confirm that 'upgradeVersion'
     // is properly propagated through your change.  Not doing so will result in a loss of user
     // settings.
-    private static final int DATABASE_VERSION = 73;
+    private static final int DATABASE_VERSION = 74;
 
     private Context mContext;
 
@@ -986,6 +986,22 @@ public class DatabaseHelper extends SQLiteOpenHelper {
             upgradeVersion = 73;
         }
 
+        if (upgradeVersion == 73) {
+            // URL from which WebView loads a JavaScript based screen-reader.
+            db.beginTransaction();
+            SQLiteStatement stmt = null;
+            try {
+                stmt = db.compileStatement("INSERT INTO secure(name,value) VALUES(?,?);");
+                loadStringSetting(stmt, Settings.Secure.ACCESSIBILITY_SCREEN_READER_URL,
+                        R.string.def_accessibility_screen_reader_url);
+                db.setTransactionSuccessful();
+            } finally {
+                db.endTransaction();
+                if (stmt != null) stmt.close();
+            }
+            upgradeVersion = 74;
+        }
+
         // *** Remember to update DATABASE_VERSION above!
 
         if (upgradeVersion != currentVersion) {
@@ -1526,6 +1542,9 @@ public class DatabaseHelper extends SQLiteOpenHelper {
 
             loadBooleanSetting(stmt, Settings.Secure.ACCESSIBILITY_SPEAK_PASSWORD,
                     R.bool.def_accessibility_speak_password);
+
+            loadStringSetting(stmt, Settings.Secure.ACCESSIBILITY_SCREEN_READER_URL,
+                    R.string.def_accessibility_screen_reader_url);
         } finally {
             if (stmt != null) stmt.close();
         }