Refactored Screenshot preference to be dependent on context preference.

Tests: Manual. 

Change-Id: I2fde1a67ade4bf89bf38b4eae0ca98074cca868c
Fixes: 30681087

res/xml/manage_assist.xml

@@ -33,6 +33,7 @@
 
     <SwitchPreference
         android:key="screenshot"
+        android:dependency="context"
         android:title="@string/assist_access_screenshot_title"
         android:summary="@string/assist_access_screenshot_summary"/>
 

src/com/android/settings/applications/ManageAssist.java

@@ -84,7 +84,6 @@ public class ManageAssist extends SettingsPreferenceFragment
             Settings.Secure.putInt(getContentResolver(), Settings.Secure.ASSIST_STRUCTURE_ENABLED,
                     (boolean) newValue ? 1 : 0);
             mHandler.post(() -> {
-                guardScreenshotPref();
                 guardFlashPref();
             });
             return true;
@@ -116,14 +115,6 @@ public class ManageAssist extends SettingsPreferenceFragment
         return false;
     }
 
-    private void guardScreenshotPref() {
-        boolean isChecked = mContextPref.isChecked();
-        boolean screenshotPrefWasSet = Settings.Secure.getInt(
-                getContentResolver(), Settings.Secure.ASSIST_SCREENSHOT_ENABLED, 1) != 0;
-        mScreenshotPref.setEnabled(isChecked);
-        mScreenshotPref.setChecked(isChecked && screenshotPrefWasSet);
-    }
-
     private void guardFlashPref() {
         ComponentName assistant = mDefaultAssitPref.getCurrentAssist();
 
@@ -163,7 +154,6 @@ public class ManageAssist extends SettingsPreferenceFragment
             mVoiceInputPref.setAssistRestrict(currentAssist);
         }
 
-        guardScreenshotPref();
         guardFlashPref();
     }