Make TestingProfile auto-create incognito profiles.

chrome/test/base/testing_profile.cc

Index: chrome/test/base/testing_profile.cc
diff --git a/chrome/test/base/testing_profile.cc b/chrome/test/base/testing_profile.cc
index d40d38394eb1e75a7079e74b0579c56b530166ff..4941c55a1a977bfb0bf1940698340c3337cfe74e 100644
--- a/chrome/test/base/testing_profile.cc
+++ b/chrome/test/base/testing_profile.cc
@@ -598,6 +598,13 @@ void TestingProfile::SetOriginalProfile(Profile* profile) {
 Profile* TestingProfile::GetOffTheRecordProfile() {
   if (IsOffTheRecord())
     return this;
+  if (!incognito_profile_) {
+    TestingProfile::Builder builder;
+    builder.SetIncognito();
+    scoped_ptr<TestingProfile> incognito_test_profile(builder.Build());
+    incognito_test_profile->SetOriginalProfile(this);
+    SetOffTheRecordProfile(incognito_test_profile.PassAs<Profile>());
+  }
   return incognito_profile_.get();
 }