Refactor: remove DeleteAll interface

There is no need for ItemUpdater to implement DeleteAll interface,
remove it.

Also make Activation::versionId private and provide a public
getVersionId() method;
Make ItemUpdater::erase() to pass const reference.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: Ifd6c61fc21b2967d6c83f1df7aaa3b2e94cae86c
diff --git a/src/item_updater.cpp b/src/item_updater.cpp
index d9a502f..49b95df 100644
--- a/src/item_updater.cpp
+++ b/src/item_updater.cpp
@@ -123,7 +123,7 @@
     return;
 }
 
-void ItemUpdater::erase(std::string versionId)
+void ItemUpdater::erase(const std::string& versionId)
 {
     auto it = versions.find(versionId);
     if (it == versions.end())
@@ -153,12 +153,6 @@
     }
 }
 
-void ItemUpdater::deleteAll()
-{
-    // TODO: when PSU's running firmware is implemented, delete all versions
-    // that are not the running firmware.
-}
-
 void ItemUpdater::createActiveAssociation(const std::string& path)
 {
     assocs.emplace_back(
@@ -268,7 +262,7 @@
     if (associations.empty())
     {
         // Remove the activation
-        erase(activationPtr->versionId);
+        erase(activationPtr->getVersionId());
     }
     else
     {