Does not crash with unexpected function in debug build.

chrome/renderer/resources/extension_process_bindings.js

 // Copyright (c) 2011 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.
 
 // This script contains privileged chrome extension related javascript APIs.
 // It is loaded by pages whose URL has the chrome-extension protocol.
 
 var chrome = chrome || {};
 (function() {
   native function GetExtensionAPIDefinition();
@@ skipping 481 matching lines @@
       var callback = function(errorMessage) {
         if (errorMessage)
           chrome.experimental.tts.speakCompleted(requestId, errorMessage);
         else
           chrome.experimental.tts.speakCompleted(requestId);
       };
       chrome.Event.prototype.dispatch.apply(this, [text, options, callback]);
     };
   }
 
+  // Get the platform from navigator.appVersion.
+  function getPlatform() {
+    var platforms = [
+      [/CrOS Touch/, "chromeos touch"],
+      [/CrOS/, "chromeos"],
+      [/Linux/, "linux"],
+      [/Mac/, "mac"],
+      [/Win/, "win"],
+    ];
+
+    for (var i = 0; i < platforms.length; i++) {
+      if (platforms[i][0].test(navigator.appVersion)) {
+        return platforms[i][1];
+      }
+    }
+    return "unknown";
+  }
+
   chromeHidden.onLoad.addListener(function (extensionId) {
     if (!extensionId) {
       return;
     }
     chrome.initExtension(extensionId, false, IsIncognitoProcess());
 
     // Setup the ChromeSetting class so we can use it to construct
     // ChromeSetting objects from the API definition.
     setupChromeSetting();
 
     // |apiFunctions| is a hash of name -> object that stores the
     // name & definition of the apiFunction. Custom handling of api functions
     // is implemented by adding a "handleRequest" function to the object.
     var apiFunctions = {};
 
     // Read api definitions and setup api functions in the chrome namespace.
     // TODO(rafaelw): Consider defining a json schema for an api definition
     //   and validating either here, in a unit_test or both.
     // TODO(rafaelw): Handle synchronous functions.
     // TOOD(rafaelw): Consider providing some convenient override points
     //   for api functions that wish to insert themselves into the call.
     var apiDefinitions = chromeHidden.JSON.parse(GetExtensionAPIDefinition());
+    var platform = getPlatform();
 
     apiDefinitions.forEach(function(apiDef) {
+      // Check platform, if apiDef has platforms key.
+      if (apiDef.platforms && apiDef.platforms.indexOf(platform) == -1) {
+        return;
+      }
+
       var module = chrome;
       var namespaces = apiDef.namespace.split('.');
       for (var index = 0, name; name = namespaces[index]; index++) {
         module[name] = module[name] || {};
         module = module[name];
       }
 
       // Add types to global validationTypes
       if (apiDef.types) {
         apiDef.types.forEach(function(t) {
@@ skipping 371 matching lines @@
 
   if (!chrome.experimental)
     chrome.experimental = {};
 
   if (!chrome.experimental.accessibility)
     chrome.experimental.accessibility = {};
 
   if (!chrome.experimental.tts)
     chrome.experimental.tts = {};
 })();