introduce tab IDs

    Tabs are identified by IDs now, instead of their position
    Refactored the save/restore code

Change-Id: I7133d55831201d097dc19ec938a85e7085f36749
diff --git a/src/com/android/browser/WebViewController.java b/src/com/android/browser/WebViewController.java
index 6028a97..bf3bdba 100644
--- a/src/com/android/browser/WebViewController.java
+++ b/src/com/android/browser/WebViewController.java
@@ -104,7 +104,7 @@
     Tab openTab(String url, boolean incognito, boolean setActive,
             boolean useCurrent);
 
-    boolean switchToTab(int tabindex);
+    boolean switchToTab(Tab tab);
 
     void closeTab(Tab tab);