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/PreloadController.java b/src/com/android/browser/PreloadController.java
index dec22ff..5de5be0 100644
--- a/src/com/android/browser/PreloadController.java
+++ b/src/com/android/browser/PreloadController.java
@@ -209,8 +209,8 @@
     }
 
     @Override
-    public void onUpdatedLockIcon(Tab tab) {
-        if (LOGD_ENABLED) Log.d(LOGTAG, "onUpdatedLockIcon()");
+    public void onUpdatedSecurityState(Tab tab) {
+        if (LOGD_ENABLED) Log.d(LOGTAG, "onUpdatedSecurityState()");
     }
 
     @Override