Revert of Revert of Clean up Smart Lock cryptohome keys logic:

chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h

Index: chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h
diff --git a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h
index ebe9c3fba162fcdf9bef9551b82d9a5406b3e478..9d838753c09b2047c39b698f42303f3e2f24dd06 100644
--- a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h
+++ b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h
@@ -11,11 +11,10 @@
 
 #include "base/callback.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
-#include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_create_keys_operation.h"
+#include "base/stl_util.h"
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_get_keys_operation.h"
-#include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.h"
+#include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_refresh_keys_operation.h"
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_types.h"
 
 namespace base {
@@ -30,8 +29,8 @@
 // A class to manage Easy unlock cryptohome keys.
 class EasyUnlockKeyManager {
  public:
-  typedef EasyUnlockCreateKeysOperation::CreateKeysCallback RefreshKeysCallback;
-  typedef EasyUnlockRemoveKeysOperation::RemoveKeysCallback RemoveKeysCallback;
+  typedef EasyUnlockRefreshKeysOperation::RefreshKeysCallback
+      RefreshKeysCallback;
   typedef EasyUnlockGetKeysOperation::GetKeysCallback GetDeviceDataListCallback;
 
   EasyUnlockKeyManager();
@@ -43,12 +42,6 @@
   void RefreshKeys(const UserContext& user_context,
                    const base::ListValue& remote_devices,
                    const RefreshKeysCallback& callback);
-
-  // Remove Easy unlock keys starting at the given index for the given
-  // |user_context|.
-  void RemoveKeys(const UserContext& user_context,
-                  size_t start_index,
-                  const RemoveKeysCallback& callback);
 
   // Retrieves the remote device data from cryptohome keys for the given
   // |user_context|.
@@ -82,6 +75,13 @@
   static std::string GetKeyLabel(size_t key_index);
 
  private:
+  // Runs the next operation if there is one. We first run all the operations in
+  // the |write_operation_queue_| and then run all the operations in the
+  // |read_operation_queue_|.
+  void RunNextOperation();
+
+  // Called when the TPM key is ready to be used for creating Easy Unlock key
+  // challenges.
   void RefreshKeysWithTpmKeyPresent(const UserContext& user_context,
                                     base::ListValue* remote_devices,
                                     const RefreshKeysCallback& callback);
@@ -89,34 +89,30 @@
   // Returns true if there are pending operations.
   bool HasPendingOperations() const;
 
-  // Returns the next operations id. Currently only used for get keys ops.
-  int GetNextOperationId();
-
-  // Runs the first pending op in |pending_ops_|. No-op if |pending_ops_| is
-  // emtpy.
-  void RunNextPendingOp();
-
-  // Callback invoked after create keys op.
-  void OnKeysCreated(size_t remove_start_index,
-                     const RefreshKeysCallback& callback,
-                     bool create_success);
-
-  // Callback invoked after remove keys op.
-  void OnKeysRemoved(const RemoveKeysCallback& callback, bool remove_success);
+  // Callback invoked after refresh keys operation.
+  void OnKeysRefreshed(const RefreshKeysCallback& callback,
+                       bool create_success);
 
   // Callback invoked after get keys op.
-  void OnKeysFetched(int op_id,
-                     const GetDeviceDataListCallback& callback,
+  void OnKeysFetched(const GetDeviceDataListCallback& callback,
                      bool fetch_success,
                      const EasyUnlockDeviceKeyDataList& fetched_data);
 
-  int operation_id_;
+  // Queued operations are stored as raw pointers, as scoped_ptrs may not behave
+  // nicely with std::deque.
+  using WriteOperationQueue = std::deque<EasyUnlockRefreshKeysOperation*>;
+  using ReadOperationQueue = std::deque<EasyUnlockGetKeysOperation*>;
+  WriteOperationQueue write_operation_queue_;
+  ReadOperationQueue read_operation_queue_;
 
-  scoped_ptr<EasyUnlockCreateKeysOperation> create_keys_op_;
-  scoped_ptr<EasyUnlockRemoveKeysOperation> remove_keys_op_;
-  std::map<int, EasyUnlockGetKeysOperation*> get_keys_ops_;
+  // Scopes the raw operation pointers to the lifetime of this object.
+  STLElementDeleter<WriteOperationQueue> write_queue_deleter_;
+  STLElementDeleter<ReadOperationQueue> read_queue_deleter_;
 
-  std::deque<base::Closure> pending_ops_;
+  // Stores the current operation in progress. At most one of these variables
+  // can be non-null at any time.
+  scoped_ptr<EasyUnlockRefreshKeysOperation> pending_write_operation_;
+  scoped_ptr<EasyUnlockGetKeysOperation> pending_read_operation_;
 
   base::WeakPtrFactory<EasyUnlockKeyManager> weak_ptr_factory_;