[sync] Automatic bootstrapping of Sync on Win 8 from cached credentials

chrome/browser/sync/profile_sync_service.h

Index: chrome/browser/sync/profile_sync_service.h
diff --git a/chrome/browser/sync/profile_sync_service.h b/chrome/browser/sync/profile_sync_service.h
index f86ce30cc87998856df88f550b7398e22f8636f0..10c3d34011cc69b6dca7f435ea4cf5ce18775602 100644
--- a/chrome/browser/sync/profile_sync_service.h
+++ b/chrome/browser/sync/profile_sync_service.h
@@ -14,6 +14,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/string16.h"
@@ -55,6 +56,9 @@ namespace sessions { class SyncSessionSnapshot; }
 
 namespace csync {
 class BaseTransaction;
+#if defined(OS_WIN)
+class CredentialCache;
+#endif
 struct SyncCredentials;
 struct UserShare;
 }
@@ -605,6 +609,27 @@ class ProfileSyncService : public browser_sync::SyncFrontend,
   // Called from Initialize() and UnsuppressAndStart().
   void TryStart();
 
+#if defined(OS_WIN)
+  // Returns true if the user is not signed in to sync, but cached credentials
+  // are available for bootstrapping sync. Returns false otherwise.
+  // Used on Windows 8 by Metro / Desktop Chrome, to prevent the user from
+  // having to sign in twice with the same account.
+  bool ShouldSigninUsingCachedCredentials();
+
+  // Attempts to load cached sync credentials from the alternate Windows 8
+  // profile in order to automatically bootstrap sync. For example, if PSS is
+  // starting up for the first time on Desktop, and the user has already signed
+  // in to sync on Metro, we look for the presence of cached credentials from
+  // the corresponding profile directory on Metro. Must be called only when
+  // ShouldSigninUsingCachedCredentials returns true.
+  void TryLoadingCachedCredentials();
+
+  // Automatically bootstraps sync using cached credentials that were
+  // successfully loaded from the alternate profile directory on Windows 8.
+  void OnLoadedCachedCredentials(
+      scoped_refptr<csync::CredentialCache> credentials);
+#endif
+
   // Puts the backend's sync scheduler into NORMAL mode.
   // Called when configuration is complete.
   void StartSyncingWithServer();
@@ -784,6 +809,10 @@ class ProfileSyncService : public browser_sync::SyncFrontend,
   // data types.
   bool setup_in_progress_;
 
+  // If true, we are bootstrapping sync using cached credentials. Happens only
+  // on Windows 8 to avoid having to sign in manually on both Metro and Desktop.
+  bool setting_up_with_cached_credentials_;
+
   // The set of currently enabled sync experiments.
   csync::Experiments current_experiments;