Identity API: Add chrome.identity.onSignInChanged routing and IDL

chrome/browser/extensions/api/identity/identity_api.cc

Index: chrome/browser/extensions/api/identity/identity_api.cc
diff --git a/chrome/browser/extensions/api/identity/identity_api.cc b/chrome/browser/extensions/api/identity/identity_api.cc
index 890f99443daecfe880f334763e2d1df758a3bb1f..206c91f2cfeb1c5a21a13682826eb7647bdd6c37 100644
--- a/chrome/browser/extensions/api/identity/identity_api.cc
+++ b/chrome/browser/extensions/api/identity/identity_api.cc
@@ -666,14 +666,20 @@ const base::Time& IdentityTokenCacheValue::expiration_time() const {
 
 IdentityAPI::IdentityAPI(Profile* profile)
     : profile_(profile),
-      error_(GoogleServiceAuthError::NONE) {
-  SigninGlobalError::GetForProfile(profile_)->AddProvider(this);
-  ProfileOAuth2TokenServiceFactory::GetForProfile(profile_)->AddObserver(this);
+      error_(GoogleServiceAuthError::NONE),
+      initialized_(false) {
 }
 
 IdentityAPI::~IdentityAPI() {
 }
 
+void IdentityAPI::Initialize() {
+  SigninGlobalError::GetForProfile(profile_)->AddProvider(this);
+  ProfileOAuth2TokenServiceFactory::GetForProfile(profile_)->AddObserver(this);
+
+  initialized_ = true;
+}
+
 IdentityMintRequestQueue* IdentityAPI::mint_queue() {
     return &mint_queue_;
 }
@@ -725,9 +731,14 @@ void IdentityAPI::ReportAuthError(const GoogleServiceAuthError& error) {
 }
 
 void IdentityAPI::Shutdown() {
+  if (!initialized_)
+    return;
+
   SigninGlobalError::GetForProfile(profile_)->RemoveProvider(this);
   ProfileOAuth2TokenServiceFactory::GetForProfile(profile_)->
       RemoveObserver(this);
+
+  initialized_ = false;
 }
 
 static base::LazyInstance<ProfileKeyedAPIFactory<IdentityAPI> >