@NonNull
        public Builder setActionButton(@NonNull Bitmap icon, @NonNull String description,
                @NonNull PendingIntent pendingIntent, boolean shouldTint) {
            Bundle bundle = new Bundle();
            bundle.putInt(KEY_ID, TOOLBAR_ACTION_BUTTON_ID);
            bundle.putParcelable(KEY_ICON, icon);
            bundle.putString(KEY_DESCRIPTION, description);
            bundle.putParcelable(KEY_PENDING_INTENT, pendingIntent);
            mIntent.putExtra(EXTRA_ACTION_BUTTON_BUNDLE, bundle);
            mIntent.putExtra(EXTRA_TINT_ACTION_BUTTON, shouldTint);
            return this;
        }
Sets the action button that is displayed in the Toolbar.
<p>
This is equivalent to calling
{@link CustomTabsIntent.Builder#addToolbarItem(int, Bitmap, String, PendingIntent)}
with {@link #TOOLBAR_ACTION_BUTTON_ID} as id.

@param icon The icon.
@param description The description for the button. To be used for accessibility.
@param pendingIntent pending intent delivered when the button is clicked.
@param shouldTint Whether the action button should be tinted.

@see CustomTabsIntent.Builder#addToolbarItem(int, Bitmap, String, PendingIntent)
customtabs/src/android/support/customtabs/CustomTabsIntent.java