[Sync] Split encryption state and logic out of PSS and SBHI.

components/sync/engine/sync_engine.h

Index: components/sync/engine/sync_engine.h
diff --git a/components/sync/engine/sync_engine.h b/components/sync/engine/sync_engine.h
index 55cd760c2e62528d888e99c7a239d6b8690dbd17..03eadfa0e20397acc5e826d7b9901af66077d572 100644
--- a/components/sync/engine/sync_engine.h
+++ b/components/sync/engine/sync_engine.h
@@ -56,6 +56,7 @@ class SyncEngine : public ModelTypeConfigurer {
     scoped_refptr<base::SingleThreadTaskRunner> sync_task_runner;
     SyncEngineHost* host = nullptr;
     std::unique_ptr<SyncBackendRegistrar> registrar;
+    std::unique_ptr<SyncEncryptionHandler::Observer> encryption_observer_proxy;
     scoped_refptr<ExtensionsActivity> extensions_activity;
     WeakHandle<JsEventHandler> event_handler;
     GURL service_url;
@@ -118,14 +119,11 @@ class SyncEngine : public ModelTypeConfigurer {
   virtual void SetEncryptionPassphrase(const std::string& passphrase,
                                        bool is_explicit) = 0;
 
-  // Use the provided passphrase to asynchronously attempt decryption. Returns
-  // false immediately if the passphrase could not be used to decrypt a locally
-  // cached copy of encrypted keys; returns true otherwise. If new encrypted
-  // keys arrive during the asynchronous call, OnPassphraseRequired may be
-  // triggered at a later time. It is an error to call this when there are no
-  // pending keys.
-  virtual bool SetDecryptionPassphrase(const std::string& passphrase)
-      WARN_UNUSED_RESULT = 0;
+  // Use the provided passphrase to asynchronously attempt decryption. If new
+  // encrypted keys arrive during the asynchronous call, OnPassphraseRequired
+  // may be triggered at a later time. It is an error to call this when there
+  // are no pending keys.
+  virtual void SetDecryptionPassphrase(const std::string& passphrase) = 0;
 
   // Kick off shutdown procedure. Attempts to cut short any long-lived or
   // blocking sync thread tasks so that the shutdown on sync thread task that
@@ -152,17 +150,6 @@ class SyncEngine : public ModelTypeConfigurer {
   // ONLY CALL THIS IF OnInitializationComplete was called!
   virtual bool HasUnsyncedItems() const = 0;
 
-  // Whether or not we are syncing encryption keys.
-  virtual bool IsNigoriEnabled() const = 0;
-
-  // Returns the type of passphrase being used to encrypt data. See
-  // sync_encryption_handler.h.
-  virtual PassphraseType GetPassphraseType() const = 0;
-
-  // If an explicit passphrase is in use, returns the time at which that
-  // passphrase was set (if available).
-  virtual base::Time GetExplicitPassphraseTime() const = 0;
-
   // True if the cryptographer has any keys available to attempt decryption.
   // Could mean we've downloaded and loaded Nigori objects, or we bootstrapped
   // using a token previously received.