[NaCl SDK] Check that browser has support for NaCl/PNaCl/PPAPI.

native_client_sdk/src/examples/common.js

 // Copyright (c) 2012 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.
 
 // Set to true when the Document is loaded IFF "test=true" is in the query
 // string.
 var isTest = false;
 
 // Javascript module pattern:
 //   see http://en.wikipedia.org/wiki/Unobtrusive_JavaScript#Namespaces
 // In essence, we define an anonymous function which is immediately called and
 // returns a new object. The new object contains only the exported definitions;
 // all other definitions in the anonymous function are inaccessible to external
 // code.
 var common = (function() {
 
+  function isHostToolchain(tool) {
+    return tool == 'win' || tool == 'linux' || tool == 'mac';
+  }
+
+  /**
+   * Return the mime type for NaCl plugin.
+   *
+   * @param {string} tool The name of the toolchain, e.g. "glibc", "newlib" etc.
+   * @param {bool} isRelease True if this is a release build.
+   * @return {string} The mime-type for the kind of NaCl plugin matching
+   * the given toolchain.
+   */
+  function mimeTypeForTool(tool, isRelease) {
+    // For NaCl modules use application/x-nacl.
+    var mimetype = 'application/x-nacl';
+    if (isHostToolchain(tool)) {
+      // For non-NaCl PPAPI plugins use the x-ppapi-debug/release
+      // mime type.
+      if (isRelease)
+        mimetype = 'application/x-ppapi-release';
+      else
+        mimetype = 'application/x-ppapi-debug';
+    } else if (tool == 'pnacl') {
+      mimetype = 'application/x-pnacl';
+    }
+    return mimetype;
+  }
+
+  /**
+   * Check if the browser supports NaCl plugins.
+   *
+   * @param {string} tool The name of the toolchain, e.g. "glibc", "newlib" etc.
+   * @return {bool} True if the browser supports the type of NaCl plugin
+   * produced by the given toolchain.
+   */
+  function browserSupportsNaCl(tool) {
+    // Assume host toolchains always work with the given browser.
+    // The below mime-type checking might not work with
+    // --register-pepper-plugins.
+    if (isHostToolchain(tool)) {
+      return true;
+    }
+    var mimetype = mimeTypeForTool(tool);
+    return navigator.mimeTypes[mimetype] !== undefined;
+  }
+
   /**
    * Create the Native Client <embed> element as a child of the DOM element
    * named "listener".
    *
    * @param {string} name The name of the example.
    * @param {string} tool The name of the toolchain, e.g. "glibc", "newlib" etc.
    * @param {string} path Directory name where .nmf file can be found.
    * @param {number} width The width to create the plugin.
    * @param {number} height The height to create the plugin.
    * @param {Object} attrs Dictionary of attributes to set on the module.
    */
   function createNaClModule(name, tool, path, width, height, attrs) {
     var moduleEl = document.createElement('embed');
     moduleEl.setAttribute('name', 'nacl_module');
     moduleEl.setAttribute('id', 'nacl_module');
     moduleEl.setAttribute('width', width);
     moduleEl.setAttribute('height', height);
     moduleEl.setAttribute('path', path);
     moduleEl.setAttribute('src', path + '/' + name + '.nmf');
 
     // Add any optional arguments
     if (attrs) {
       for (var key in attrs) {
         moduleEl.setAttribute(key, attrs[key])
       }
     }
 
-    // For NaCL modules use application/x-nacl.
-    var mimetype = 'application/x-nacl';
-    var isHost = tool == 'win' || tool == 'linux' || tool == 'mac';
-    if (isHost) {
-      // For non-nacl PPAPI plugins use the x-ppapi-debug/release
-      // mime type.
-      if (path.toLowerCase().indexOf('release') != -1)
-        mimetype = 'application/x-ppapi-release';
-      else
-        mimetype = 'application/x-ppapi-debug';
-    } else if (tool == 'pnacl') {
-      mimetype = 'application/x-pnacl';
-    }
+    var mimetype = mimeTypeForTool(tool);
     moduleEl.setAttribute('type', mimetype);
 
     // The <EMBED> element is wrapped inside a <DIV>, which has both a 'load'
     // and a 'message' event listener attached.  This wrapping method is used
     // instead of attaching the event listeners directly to the <EMBED> element
     // to ensure that the listeners are active before the NaCl module 'load'
     // event fires.
     var listenerDiv = document.getElementById('listener');
     listenerDiv.appendChild(moduleEl);
 
     // Host plugins don't send a moduleDidLoad message. We'll fake it here.
+    var isHost = isHostToolchain(tool);
     if (isHost) {
       window.setTimeout(function() {
         var evt = document.createEvent('Event');
         evt.initEvent('load', true, true);  // bubbles, cancelable
         moduleEl.dispatchEvent(evt);
       }, 100);  // 100 ms
     }
 
     // This is code that is only used to test the SDK.
     if (isTest) {
@@ skipping 173 matching lines @@
    * @param {string} path Directory name where .nmf file can be found.
    * @param {number} width The width to create the plugin.
    * @param {number} height The height to create the plugin.
    * @param {Object} attrs Optional dictionary of additional attributes.
    */
   function domContentLoaded(name, tool, path, width, height, attrs) {
     // If the page loads before the Native Client module loads, then set the
     // status message indicating that the module is still loading.  Otherwise,
     // do not change the status message.
     updateStatus('Page loaded.');
-    if (common.naclModule == null) {
+    var isRelease = path.toLowerCase().indexOf('release') != -1;
+    if (!browserSupportsNaCl(tool, isRelease)) {
+      updateStatus(
+          'Browser does not support NaCl (' + tool + '), or NaCl is disabled');
+    } else if (common.naclModule == null) {
       updateStatus('Creating embed: ' + tool);
 
       // We use a non-zero sized embed to give Chrome space to place the bad
       // plug-in graphic, if there is a problem.
       width = typeof width !== 'undefined' ? width : 200;
       height = typeof height !== 'undefined' ? height : 200;
       attachDefaultListeners();
       createNaClModule(name, tool, path, width, height, attrs);
     } else {
       // It's possible that the Native Client module onload event fired
@@ skipping 87 matching lines @@
       var pathFormat = body.dataset.path;
       var path = pathFormat.replace('{tc}', tc).replace('{config}', config);
 
       isTest = searchVars.test === 'true';
 
       loadFunction(body.dataset.name, tc, path, body.dataset.width,
                    body.dataset.height, attrs);
     }
   }
 });