Add a mimeHandler extension API.

chrome/browser/resources/pdf/background.js

-// Copyright 2013 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.
-
-(function() {
-  'use strict';
-
-  /**
-   * A map of view ID (which identifies a particular PDF viewer instance) to
-   * stream object.
-   * @type {Object.<string, Object>}
-   */
-  var streams = {};
-
-  /**
-   * A map of view ID (which identifies a particular PDF viewer instance) to
-   * initialization function for that view.
-   * @type {Object.<string, Function>}
-   */
-  var pluginInitFunctions = {};
-
-  /**
-   * If we have received a stream object and an initialization function for a
-   * particular PDF viewer instance we know that the extension has loaded in
-   * and we can pass it the stream. We can then delete the corresponding map
-   * entries.
-   * @param {string} viewId The ID of the view to initialize with a stream.
-   */
-  function flush(viewId) {
-    if (viewId in streams && viewId in pluginInitFunctions) {
-      pluginInitFunctions[viewId](streams[viewId]);
-      delete streams[viewId];
-      delete pluginInitFunctions[viewId];
-    }
-  }
-
-  /**
-   * This is called when loading a document with the PDF mime type and passes a
-   * stream that points to the PDF file. This may be run before or after we
-   * receive a message from the PDF viewer with its initialization function.
-   */
-  chrome.streamsPrivate.onExecuteMimeTypeHandler.addListener(
-    function(streamDetails) {
-      // Store the stream until we are contacted by the PDF viewer that owns the
-      // stream.
-      streams[streamDetails.viewId] = streamDetails;
-      flush(streamDetails.viewId);
-    }
-  );
-
-  /**
-   * This is called when we receive a message from the PDF viewer indicating
-   * it has loaded and is ready to receive a stream of the data.
-   */
-  chrome.runtime.onMessage.addListener(
-    function(request, sender, responseFunction) {
-      // Store the initialization function until we receive the stream which
-      // corresponds to the PDF viewer.
-      pluginInitFunctions[request.viewId] = responseFunction;
-      flush(request.viewId);
-    }
-  );
-}());