Fix indentation in preference fragments.

Unfortunately, while there does exist an XML property to disable the
indentation, it's bugged for category headings, so we have to do this
silly thing where we strip the padding in the adapter. Hopefully they'll
fix the bug and we can move to use the sanctioned property.

See: https://issuetracker.google.com/issues/111662669

Fixes #8233

src/org/thoughtcrime/securesms/preferences/CorrectedPreferenceFragment.java

@@ -1,12 +1,21 @@
 package org.thoughtcrime.securesms.preferences;
 
 
+import android.annotation.SuppressLint;
 import android.os.Bundle;
 import android.support.v4.app.DialogFragment;
+import android.support.v4.view.ViewCompat;
 import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceCategory;
 import android.support.v7.preference.PreferenceFragmentCompat;
+import android.support.v7.preference.PreferenceGroupAdapter;
+import android.support.v7.preference.PreferenceScreen;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.support.v7.widget.RecyclerView;
 import android.view.View;
+import android.view.ViewGroup;
 
+import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.components.CustomDefaultPreference;
 import org.thoughtcrime.securesms.preferences.widgets.ColorPickerPreference;
 import org.thoughtcrime.securesms.preferences.widgets.ColorPickerPreferenceDialogFragmentCompat;
@@ -44,5 +53,33 @@ public abstract class CorrectedPreferenceFragment extends PreferenceFragmentComp
     }
   }
 
+  @Override
+  protected RecyclerView.Adapter onCreateAdapter(PreferenceScreen preferenceScreen) {
+    return new PreferenceGroupAdapter(preferenceScreen) {
+      @SuppressLint("RestrictedApi")
+      @Override
+      public void onBindViewHolder(PreferenceViewHolder holder, int position) {
+        super.onBindViewHolder(holder, position);
+        Preference preference = getItem(position);
+        if (preference instanceof PreferenceCategory) {
+          setZeroPaddingToLayoutChildren(holder.itemView);
+        } else {
+          View iconFrame = holder.itemView.findViewById(R.id.icon_frame);
+          if (iconFrame != null) {
+            iconFrame.setVisibility(preference.getIcon() == null ? View.GONE : View.VISIBLE);
+          }
+        }
+      }
+    };
+  }
 
+  private void setZeroPaddingToLayoutChildren(View view) {
+    if (!(view instanceof ViewGroup)) return;
+
+    ViewGroup viewGroup = (ViewGroup) view;
+    for (int i = 0; i < viewGroup.getChildCount(); i++) {
+      setZeroPaddingToLayoutChildren(viewGroup.getChildAt(i));
+      ViewCompat.setPaddingRelative(viewGroup, 0, viewGroup.getPaddingTop(), ViewCompat.getPaddingEnd(viewGroup), viewGroup.getPaddingBottom());
+    }
+  }
 }