[NavigatonView] Bottom scrim is always displayed when setting android:theme

[tadfisher]

Description: NavigationView has logic to determine whether to display the insetForeground scrim in the bottom system window inset. This logic does not apply when android:theme is set for the view, as it is checking that the view's context is an instance of Activity, and setting a theme on the view replaces the context with a ContextThemeWrapper.

Expected behavior: When setting android:theme on a NavigationView with a non-transparent navigationBarColor applied to the window, the view should not draw insetForeground in the bottom system window inset area.

Source code: From NavigationView.java, in setupInsetScrimsListener:

        Context context = getContext();
        if (context instanceof Activity && VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
          boolean isBehindSystemNav =
              ((Activity) context).findViewById(android.R.id.content).getHeight()
                  == getHeight();
          boolean hasNonZeroAlpha =
              Color.alpha(((Activity) context).getWindow().getNavigationBarColor()) != 0;

          setDrawBottomInsetForeground(isBehindSystemNav && hasNonZeroAlpha);
        }

If the Context is actually a ContextThemeWrapper or ContextWrapper instance, the logic is not performed and the view will draw the bottom inset foreground by default.

Android API version: 29

Material Library version: 1.2.0

Device: Pixel 2 XL