[Projector] Label by should appear even if no color map options are available.

• TensorBoard and TensorFlow version 1.8
• OS Platform and version (Linux Ubuntu 17.10)
• Python version (2.7.14)
• Browser: Safari version 11.1.1 (13605.2.8)

If no metadata column meets the conditions to be used as a colormap (ie it has less than 50 unique values, or it is numeric), the section with label by and color by does not appear in the Tensorboard projector interface.

 <div hidden$="[[!_hasChoices(colorOptions)]]">
    <div class="colorlabel-container">
      <!-- Label by -->
      <paper-dropdown-menu id="labelby" no-animations label="Label by">
        <paper-listbox attr-for-selected="value" class="dropdown-content" selected="{{selectedLabelOption}}" slot="dropdown-content">
          <template is="dom-repeat" items="[[labelOptions]]">
            <paper-item value="[[item]]" label="[[item]]">
              [[item]]
            </paper-item>
          </template>
        </paper-listbox>
      </paper-dropdown-menu>
      <!-- Color by -->
      <paper-dropdown-menu id="colorby" no-animations label="Color by">
        <paper-listbox attr-for-selected="value" class="dropdown-content" selected="{{selectedColorOptionName}}" slot="dropdown-content">
          <template is="dom-repeat" items="[[colorOptions]]">
            <paper-item class$="[[getSeparatorClass(item.isSeparator)]]" value="[[item.name]]" label="[[item.name]]" disabled="[[item.isSeparator]]">
              [[item.name]]
              <span class="item-details">[[item.desc]]</span>
            </paper-item>
          </template>
        </paper-listbox>
      </paper-dropdown-menu>
    </div>

Despite this, there could be interesting columns to show as a label in the metadata.
From an interface point of view would not it be better to show both options anyway with the message 'No colormap'?

Start in the TensorBoard Projector interface at the markup containing hidden$="[[!_hasChoices(colorOptions)]]" and the Label by/Color by dropdowns. Inspect how labelOptions and colorOptions are populated when no colormap is available, then verify that Label by remains visible and Color by communicates that no colormap is available.