Add setting to disable keyguard widgets

This allows disabling keyguard widgets through Settings.
On new devices, the setting is turned off by default.  If the
user currently has widgets in keyguard, then we keep them
and re-enable the setting.

Change-Id: I25f0756ac72227e13dcb491694b3ec3c2bf1d293

res/xml/security_settings_biometric_weak.xml

@@ -51,6 +51,10 @@
             android:key="power_button_instantly_locks"
             android:title="@string/lockpattern_settings_enable_power_button_instantly_locks"/>
 
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"

res/xml/security_settings_chooser.xml

@@ -26,6 +26,10 @@
             android:summary="@string/unlock_set_unlock_mode_none"
             android:persistent="false"/>
 
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"

res/xml/security_settings_lockscreen.xml

@@ -25,6 +25,11 @@
             android:title="@string/unlock_set_unlock_launch_picker_title"
             android:summary="@string/unlock_set_unlock_mode_off"
             android:persistent="false"/>
+
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"

res/xml/security_settings_password.xml

@@ -38,6 +38,10 @@
             android:key="power_button_instantly_locks"
             android:title="@string/lockpattern_settings_enable_power_button_instantly_locks"/>
 
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"

res/xml/security_settings_pattern.xml

@@ -42,6 +42,10 @@
             android:key="power_button_instantly_locks"
             android:title="@string/lockpattern_settings_enable_power_button_instantly_locks"/>
 
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"

res/xml/security_settings_pin.xml

@@ -38,6 +38,10 @@
             android:key="power_button_instantly_locks"
             android:title="@string/lockpattern_settings_enable_power_button_instantly_locks"/>
 
+        <CheckBoxPreference
+            android:key="keyguard_enable_widgets"
+            android:title="@string/security_enable_widgets_title"/>
+
         <PreferenceScreen
             android:fragment="com.android.settings.OwnerInfoSettings"
             android:key="owner_info_settings"