Add API in developerPrivate to allow/ disallow incognito mode.

chrome/browser/extensions/api/developer_private/developer_private_api.cc

Index: chrome/browser/extensions/api/developer_private/developer_private_api.cc
diff --git a/chrome/browser/extensions/api/developer_private/developer_private_api.cc b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
index fb75d205dba086a1e4fe19de2248c4e3a7d29652..474a7ebb7be1eb1a21b3373be0c665350ad1f32b 100644
--- a/chrome/browser/extensions/api/developer_private/developer_private_api.cc
+++ b/chrome/browser/extensions/api/developer_private/developer_private_api.cc
@@ -409,6 +409,30 @@ bool DeveloperPrivateAllowFileAccessFunction::RunImpl() {
 DeveloperPrivateAllowFileAccessFunction::
     ~DeveloperPrivateAllowFileAccessFunction() {}
 
+bool DeveloperPrivateAllowIncognitoFunction::RunImpl() {
+  std::string extension_id;
+  bool allow = false;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &extension_id));
+  EXTENSION_FUNCTION_VALIDATE(args_->GetBoolean(1, &allow));
+
+  ExtensionService* service = profile()->GetExtensionService();
+  const Extension* extension = service->GetInstalledExtension(extension_id);
+  bool result = true;
+
+  if (!extension) {
+    result = false;
+  } else {
+    service->SetIsIncognitoEnabled(extension->id(), allow);
+  }
+
+  SetResult(Value::CreateBooleanValue(result));

[asargent_no_longer_on_chrome, 2013/02/22 00:04:06]

nit: instead of a boolean result passed as an argument to a callback function,
you should instead have a void callback function and then just return |result|
instead of always returning true here. 

When you return false from an ExtensionFunction, the callback in JS
automatically can find out about the error by examining the
chrome.runtime.lastError variable. 

[Gaurav, 2013/02/25 18:26:51]

Done.

+  return true;
+}
+
+DeveloperPrivateAllowIncognitoFunction::
+    ~DeveloperPrivateAllowIncognitoFunction() {}
+
+
 bool DeveloperPrivateReloadFunction::RunImpl() {
   std::string extension_id;
   EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &extension_id));