Rename Tab.LockIcon to Tab.SecurityState

The tab's state is concerned with whether or not the page is secure. It should
not mention the lock icon, as this is just a UI choice of how to represent the
security state.

Also renames WebViewController.onUpdatedLockIcon() to onUpdatedSecurityState().

No functional change.

Bug: 5403366
Change-Id: Id18402e84fd9b1f661c160189c7a19a9352fd25c
diff --git a/src/com/android/browser/Controller.java b/src/com/android/browser/Controller.java
index 78d0077..602df06 100644
--- a/src/com/android/browser/Controller.java
+++ b/src/com/android/browser/Controller.java
@@ -880,7 +880,7 @@
     }
 
     @Override
-    public void onUpdatedLockIcon(Tab tab) {
+    public void onUpdatedSecurityState(Tab tab) {
         mUi.onTabDataChanged(tab);
     }