Propagate browser zoom changes to embedded PDFs.

chrome/browser/resources/pdf/browser_api.js

 // 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.
 
 'use strict';
 
 /**
- * Returns a promise that will resolve to the default zoom factor.
- * @param {!Object} streamInfo The stream object pointing to the data contained
- *     in the PDF.
- * @return {Promise<number>} A promise that will resolve to the default zoom
- *     factor.
- */
-function lookupDefaultZoom(streamInfo) {
-  // Webviews don't run in tabs so |streamInfo.tabId| is -1 when running within
-  // a webview.
-  if (!chrome.tabs || streamInfo.tabId < 0)
-    return Promise.resolve(1);
-
-  return new Promise(function(resolve, reject) {
-    chrome.tabs.getZoomSettings(streamInfo.tabId, function(zoomSettings) {
-      resolve(zoomSettings.defaultZoomFactor);
-    });
-  });
-}
-
-/**
  * Returns a promise that will resolve to the initial zoom factor
  * upon starting the plugin. This may differ from the default zoom
  * if, for example, the page is zoomed before the plugin is run.
  * @param {!Object} streamInfo The stream object pointing to the data contained
  *     in the PDF.
  * @return {Promise<number>} A promise that will resolve to the initial zoom
  *     factor.
  */
 function lookupInitialZoom(streamInfo) {
   // Webviews don't run in tabs so |streamInfo.tabId| is -1 when running within
   // a webview.
   if (!chrome.tabs || streamInfo.tabId < 0)
     return Promise.resolve(1);
 
   return new Promise(function(resolve, reject) {
     chrome.tabs.getZoom(streamInfo.tabId, resolve);
   });
 }
 
 /**
  * A class providing an interface to the browser.
  */
 class BrowserApi {
   /**
    * @constructor
    * @param {!Object} streamInfo The stream object which points to the data
    *     contained in the PDF.
-   * @param {number} defaultZoom The default browser zoom.
    * @param {number} initialZoom The initial browser zoom
    *     upon starting the plugin.
-   * @param {boolean} manageZoom Whether to manage zoom.
+   * @param {BrowserApi.ZoomBehaviour} zoomBehaviour How to manage zoom.
    */
-  constructor(streamInfo, defaultZoom, initialZoom, manageZoom) {
+  constructor(streamInfo, initialZoom, zoomBehaviour) {
     this.streamInfo_ = streamInfo;
-    this.defaultZoom_ = defaultZoom;
     this.initialZoom_ = initialZoom;
-    this.manageZoom_ = manageZoom;
+    this.zoomBehaviour_ = zoomBehaviour;
   }
 
   /**
    * Returns a promise to a BrowserApi.
    * @param {!Object} streamInfo The stream object pointing to the data
    *     contained in the PDF.
-   * @param {boolean} manageZoom Whether to manage zoom.
+   * @param {BrowserApi.ZoomBehaviour} zoomBehaviour How to manage zoom.
    */
-  static create(streamInfo, manageZoom) {
-    return Promise.all([
-        lookupDefaultZoom(streamInfo),
-        lookupInitialZoom(streamInfo)
-    ]).then(function(zoomFactors) {
+  static create(streamInfo, zoomBehaviour) {
+    return lookupInitialZoom(streamInfo).then(function(initialZoom) {
       return new BrowserApi(
-          streamInfo, zoomFactors[0], zoomFactors[1], manageZoom);
+          streamInfo, initialZoom, zoomBehaviour);
     });
   }
 
   /**
    * Returns the stream info pointing to the data contained in the PDF.
    * @return {Object} The stream info object.
    */
   getStreamInfo() {
     return this.streamInfo_;
   }
 
   /**
    * Aborts the stream.
    */
   abortStream() {
     if (chrome.mimeHandlerPrivate)
       chrome.mimeHandlerPrivate.abortStream();
   }
 
   /**
    * Sets the browser zoom.
    * @param {number} zoom The zoom factor to send to the browser.
    * @return {Promise} A promise that will be resolved when the browser zoom
    *     has been updated.
    */
   setZoom(zoom) {
-    if (!this.manageZoom_)
-      return Promise.resolve();
+    if (this.zoomBehaviour_ != BrowserApi.ZoomBehaviour.MANAGE)
+      return Promise.reject(new Error('Viewer does not manage browser zoom.'));
     return new Promise(function(resolve, reject) {
       chrome.tabs.setZoom(this.streamInfo_.tabId, zoom, resolve);
     }.bind(this));
   }
 
   /**
-   * Returns the default browser zoom factor.
-   * @return {number} The default browser zoom factor.
-   */
-  getDefaultZoom() {
-    return this.defaultZoom_;
-  }
-
-  /**
    * Returns the initial browser zoom factor.
    * @return {number} The initial browser zoom factor.
    */
   getInitialZoom() {
     return this.initialZoom_;
   }
 
   /**
+   * Returns how to manage the zoom.
+   * @return {BrowserApi.ZoomBehaviour} How to manage zoom.
+   */
+  getZoomBehaviour() {
+    return this.zoomBehaviour_;
+  }
+
+  /**
    * Adds an event listener to be notified when the browser zoom changes.
    * @param {function} listener The listener to be called with the new zoom
    *     factor.
    */
   addZoomEventListener(listener) {
-    if (!this.manageZoom_)
+    if (!(this.zoomBehaviour_ == BrowserApi.ZoomBehaviour.MANAGE ||
+          this.zoomBehaviour_ == BrowserApi.ZoomBehaviour.PROPAGATE_PARENT))
       return;
 
     chrome.tabs.onZoomChange.addListener(function(zoomChangeInfo) {
       if (zoomChangeInfo.tabId != this.streamInfo_.tabId)
         return;
       listener(zoomChangeInfo.newZoomFactor);
     }.bind(this));
   }
 };
 
 /**
+ * Enumeration of ways to manage zoom changes.
+ * @enum {number}
+ */
+BrowserApi.ZoomBehaviour = {
+  NONE: 0,
+  MANAGE: 1,
+  PROPAGATE_PARENT: 2
+};
+
+/**
  * Creates a BrowserApi for an extension running as a mime handler.
  * @return {Promise<BrowserApi>} A promise to a BrowserApi instance constructed
  *     using the mimeHandlerPrivate API.
  */
 function createBrowserApiForMimeHandlerView() {
   return new Promise(function(resolve, reject) {
     chrome.mimeHandlerPrivate.getStreamInfo(resolve);
   }).then(function(streamInfo) {
     let promises = [];
-    let manageZoom = !streamInfo.embedded && streamInfo.tabId != -1;
+    let zoomBehaviour = BrowserApi.ZoomBehaviour.NONE;
     if (streamInfo.tabId != -1) {
+      zoomBehaviour = streamInfo.embedded ?
+                      BrowserApi.ZoomBehaviour.PROPAGATE_PARENT :
+                      BrowserApi.ZoomBehaviour.MANAGE;
       promises.push(new Promise(function(resolve) {
         chrome.tabs.get(streamInfo.tabId, resolve);
       }).then(function(tab) {
         if (tab)
           streamInfo.tabUrl = tab.url;
       }));
     }
-    if (manageZoom) {
+    if (zoomBehaviour == BrowserApi.ZoomBehaviour.MANAGE) {
       promises.push(new Promise(function(resolve) {
         chrome.tabs.setZoomSettings(
             streamInfo.tabId, {mode: 'manual', scope: 'per-tab'}, resolve);
       }));
     }
     return Promise.all(promises).then(
-        function() { return BrowserApi.create(streamInfo, manageZoom); });
+        function() { return BrowserApi.create(streamInfo, zoomBehaviour); });
   });
 }
 
 /**
  * Creates a BrowserApi instance for an extension not running as a mime handler.
  * @return {Promise<BrowserApi>} A promise to a BrowserApi instance constructed
  *     from the URL.
  */
 function createBrowserApiForPrintPreview() {
   let url = window.location.search.substring(1);
   let streamInfo = {
     streamUrl: url,
     originalUrl: url,
     responseHeaders: {},
     embedded: window.parent != window,
     tabId: -1,
   };
   return new Promise(function(resolve, reject) {
     if (!chrome.tabs) {
       resolve();
       return;
     }
     chrome.tabs.getCurrent(function(tab) {
       streamInfo.tabId = tab.id;
       streamInfo.tabUrl = tab.url;
       resolve();
     });
-  }).then(function() { return BrowserApi.create(streamInfo, false); });
+  }).then(function() {
+    return BrowserApi.create(streamInfo, BrowserApi.ZoomBehaviour.NONE);
+  });
 }
 
 /**
  * Returns a promise that will resolve to a BrowserApi instance.
  * @return {Promise<BrowserApi>} A promise to a BrowserApi instance for the
  *     current environment.
  */
 function createBrowserApi() {
   if (location.origin === 'chrome://print') {
     return createBrowserApiForPrintPreview();
   }
 
   return createBrowserApiForMimeHandlerView();
 }