Part 1 of work to do user sign in based on OAuth2:

chrome/common/net/gaia/gaia_urls.cc

Index: chrome/common/net/gaia/gaia_urls.cc
===================================================================
--- chrome/common/net/gaia/gaia_urls.cc	(revision 110361)
+++ chrome/common/net/gaia/gaia_urls.cc	(working copy)
@@ -24,6 +24,20 @@
 const char kOAuth1LoginUrlSuffix[] = "/accounts/OAuthLogin";
 const char kOAuthRevokeTokenUrlSuffix[] = "/accounts/AuthSubRevokeToken";
 
+// OAuth2 client id for Google Chrome which is registered as an
+// installed application.
+static const char kOAuth2ChromeClientId[] =
+    "77185425430.apps.googleusercontent.com";
+// For an installed application, client secret is not really a secret since
+// it is expected to be embeeded in the application.
+// See documentation at
+// http://code.google.com/apis/accounts/docs/OAuth2InstalledApp.html
+static const char kOAuth2ChromeClientSecret[] =
+    "OTJgUOQcT7lO7GsGZq2G4IlT";
+const char kClientLoginToOAuth2Url[] =
+    "https://accounts.google.com/o/oauth2/programmatic_auth";
+const char kOAuth2TokenUrl[] =
+    "https://accounts.google.com/o/oauth2/token";
 }  // namespacce
 
 GaiaUrls* GaiaUrls::GetInstance() {
@@ -61,6 +75,11 @@
   oauth_user_info_url_ = "https://www.googleapis.com/oauth2/v1/userinfo";
   oauth_wrap_bridge_user_info_scope_ =
       "https://www.googleapis.com/auth/userinfo.email";
+
+  oauth2_chrome_client_id_ = kOAuth2ChromeClientId;
+  oauth2_chrome_client_secret_ = kOAuth2ChromeClientSecret;
+  client_login_to_oauth2_url_ = kClientLoginToOAuth2Url;
+  oauth2_token_url_ = kOAuth2TokenUrl;
 }
 
 GaiaUrls::~GaiaUrls() {
@@ -125,3 +144,19 @@
 const std::string& GaiaUrls::oauth_wrap_bridge_user_info_scope() {
   return oauth_wrap_bridge_user_info_scope_;
 }
+
+const std::string& GaiaUrls::oauth2_chrome_client_id() {
+  return oauth2_chrome_client_id_;
+}
+
+const std::string& GaiaUrls::oauth2_chrome_client_secret() {
+  return oauth2_chrome_client_secret_;
+}
+
+const std::string& GaiaUrls::client_login_to_oauth2_url() {
+  return client_login_to_oauth2_url_;
+}
+
+const std::string& GaiaUrls::oauth2_token_url() {
+  return oauth2_token_url_;
+}