Update customize button title when state changed

- This CL update customize button title when
  onCustomizedButtonStateChanged() is called.
- Add test case

Bug: 152002708
Test: make -j42 RunSettingsRoboTests
Change-Id: I85c9cf90305757e279c058db2875e303b4add437

tests/robotests/src/com/android/settings/panel/FakePanelContent.java

@@ -46,6 +46,8 @@ public class FakePanelContent implements PanelContent {
     private CharSequence mSubTitle;
     private IconCompat mIcon;
     private int mViewType;
+    private boolean mIsCustomizedButtonUsed = false;
+    private CharSequence mCustomizedButtonTitle;
 
     @Override
     public IconCompat getIcon() {
@@ -97,4 +99,22 @@ public class FakePanelContent implements PanelContent {
     public int getViewType() {
         return mViewType;
     }
+
+    @Override
+    public boolean isCustomizedButtonUsed() {
+        return mIsCustomizedButtonUsed;
+    }
+
+    public void setIsCustomizedButtonUsed(boolean isUsed) {
+        mIsCustomizedButtonUsed = isUsed;
+    }
+
+    @Override
+    public CharSequence getCustomizedButtonTitle() {
+        return mCustomizedButtonTitle;
+    }
+
+    public void setCustomizedButtonTitle(CharSequence title) {
+        mCustomizedButtonTitle = title;
+    }
 }