Re-implement UserAgent in browser

- Remove calls to SWE's WebSetting API and use the newer implementation of
  the engine. The newer implementation tracks UserAgent per navigation
  entry.
- Allow to override the UserAgent using command line switches.
- Remove debug option to change UserAgent string.
- BrowserConfig class cleanup.

Change-Id: Ib1cc4763e0cbf0207793d1f4e6b1644a9dbb5c08
diff --git a/src/com/android/browser/CrashLogExceptionHandler.java b/src/com/android/browser/CrashLogExceptionHandler.java
index 9207570..67beaab 100644
--- a/src/com/android/browser/CrashLogExceptionHandler.java
+++ b/src/com/android/browser/CrashLogExceptionHandler.java
@@ -82,7 +82,7 @@
 
     public CrashLogExceptionHandler(Context ctx) {
         mAppContext = ctx;
-        BrowserCommandLine cl = new BrowserCommandLine();
+        BrowserCommandLine cl = BrowserCommandLine.getInstance();
         if (cl.hasSwitch(CRASH_LOG_SERVER_CMD)) {
             mLogServer = cl.getSwitchValue(CRASH_LOG_SERVER_CMD);
             if (mLogServer != null) {