Fix Talkback say twice in MainSwitch

- Remove the duplicated setting in the ContentDescription.

Bug: 191735947
Test: manual test
Test: make RunSettingsLibRoboTests -j ROBOTEST_FILTER=com.android.settingslib.widget
Change-Id: If28d0002dd1087173623b654c67bc7597d721a85

packages/SettingsLib/MainSwitchPreference/src/com/android/settingslib/widget/MainSwitchBar.java

@@ -152,9 +152,6 @@ public class MainSwitchBar extends LinearLayout implements CompoundButton.OnChec
     public void setTitle(CharSequence text) {
         if (mTextView != null) {
             mTextView.setText(text);
-            if (mSwitch != null) {
-                mSwitch.setContentDescription(mTextView.getText());
-            }
         }
     }
 

packages/SettingsLib/tests/robotests/src/com/android/settingslib/widget/MainSwitchBarTest.java

@@ -19,6 +19,7 @@ package com.android.settingslib.widget;
 import static com.google.common.truth.Truth.assertThat;
 
 import android.content.Context;
+import android.text.TextUtils;
 import android.view.View;
 import android.widget.Switch;
 import android.widget.TextView;
@@ -59,13 +60,13 @@ public class MainSwitchBarTest {
     }
 
     @Test
-    public void setTitle_switchShouldHasContentDescription() {
+    public void setTitle_switchShouldNotHasContentDescription() {
         final String title = "title";
 
         mBar.setTitle(title);
 
         final Switch switchObj = mBar.getSwitch();
-        assertThat(switchObj.getContentDescription()).isEqualTo(title);
+        assertThat(TextUtils.isEmpty(switchObj.getContentDescription())).isTrue();
     }
 
     @Test