Add a SigninAllowed policy.

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 fa809eb0383843bc70a612d50a345fc686818480..194a9ced33385cc8a4bd3c3347ae6ebae0bee182 100644
--- a/chrome/test/base/testing_profile.cc
+++ b/chrome/test/base/testing_profile.cc
@@ -162,6 +162,7 @@ TestingProfile::TestingProfile()
     : start_time_(Time::Now()),
       testing_prefs_(NULL),
       incognito_(false),
+      original_profile_(NULL),
       last_session_exited_cleanly_(true),
       profile_dependency_manager_(ProfileDependencyManager::GetInstance()),
       delegate_(NULL) {
@@ -176,6 +177,7 @@ TestingProfile::TestingProfile(const FilePath& path)
     : start_time_(Time::Now()),
       testing_prefs_(NULL),
       incognito_(false),
+      original_profile_(NULL),
       last_session_exited_cleanly_(true),
       profile_path_(path),
       profile_dependency_manager_(ProfileDependencyManager::GetInstance()),
@@ -189,6 +191,7 @@ TestingProfile::TestingProfile(const FilePath& path,
     : start_time_(Time::Now()),
       testing_prefs_(NULL),
       incognito_(false),
+      original_profile_(NULL),
       last_session_exited_cleanly_(true),
       profile_path_(path),
       profile_dependency_manager_(ProfileDependencyManager::GetInstance()),
@@ -213,6 +216,7 @@ TestingProfile::TestingProfile(
       prefs_(prefs.release()),
       testing_prefs_(NULL),
       incognito_(off_the_record),
+      original_profile_(NULL),
       last_session_exited_cleanly_(true),
       extension_special_storage_policy_(extension_policy),
       profile_path_(path),
@@ -499,6 +503,10 @@ void TestingProfile::SetOffTheRecordProfile(Profile* profile) {
   incognito_profile_.reset(profile);
 }
 
+void TestingProfile::SetOriginalProfile(Profile* profile) {
+  original_profile_ = profile;
+}
+
 Profile* TestingProfile::GetOffTheRecordProfile() {
   return incognito_profile_.get();
 }
@@ -508,6 +516,8 @@ bool TestingProfile::HasOffTheRecordProfile() {
 }
 
 Profile* TestingProfile::GetOriginalProfile() {
+  if (original_profile_)
+    return original_profile_;
   return this;
 }