Add user selectable Default Browser feature

- add Default Apps section in Apps / Advanced
- follow UX spec

This change depends on a Framework change which adds new APIs in PackageMaager
for setting and getting the default Browser App package name.

See bug #20144393

Change-Id: I2ff456eeaced9f740f4dd6fb6bccea6de6ea1308

src/com/android/settings/InstrumentedFragment.java

@@ -23,9 +23,11 @@ import com.android.internal.logging.MetricsLogger;
  * Instrumented fragment that logs visibility state.
  */
 public abstract class InstrumentedFragment extends PreferenceFragment {
-    // Declare new temproary categories here, starting after this value.
+    // Declare new temporary categories here, starting after this value.
     public static final int VIEW_CATEGORY_UNDECLARED = 100000;
 
+    public static final int VIEW_CATEGORY_DEFAULT_APPS = VIEW_CATEGORY_UNDECLARED + 1;
+
     /**
      * Declare the view of this category.
      *