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 504 matching lines @@
     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());
 
+    // Get the platform from navigator.appVersion.
+    var platform = "unknown";

[Matt Perry, 2011/06/07 00:15:52]

nit: can you move this block into a separate getPlatform function?

[Peng, 2011/06/07 19:17:30]

Done.

+    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)) {
+        platform = platforms[i][1];
+        break;
+      }
+    }
+
     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 = {};
 })();