Add support for a "split" incognito behavior for extensions.

chrome/renderer/resources/renderer_extension_bindings.js

Index: chrome/renderer/resources/renderer_extension_bindings.js
diff --git a/chrome/renderer/resources/renderer_extension_bindings.js b/chrome/renderer/resources/renderer_extension_bindings.js
index 3d6228e05cf5ae2f64cc3b03f1e6f2b72e26bd54..5a2c7315c5672c3301cc18a25f169744d4d631b1 100644
--- a/chrome/renderer/resources/renderer_extension_bindings.js
+++ b/chrome/renderer/resources/renderer_extension_bindings.js
@@ -143,14 +143,15 @@ var chrome = chrome || {};
   // This function is called on context initialization for both content scripts
   // and extension contexts.
   chrome.initExtension = function(extensionId, warnOnPrivilegedApiAccess,
-                                  inIncognitoTab) {
+                                  inIncognitoContext) {
     delete chrome.initExtension;
     chromeHidden.extensionId = extensionId;
 
     chrome.extension = chrome.extension || {};
     chrome.self = chrome.extension;
 
-    chrome.extension.inIncognitoTab = inIncognitoTab;
+    chrome.extension.inIncognitoTab = inIncognitoContext;  // deprecated
+    chrome.extension.inIncognitoContext = inIncognitoContext;
 
     // Events for when a message channel is opened to our extension.
     chrome.extension.onConnect = new chrome.Event();