Add CSS spinner while loading locks content (#527)

* Add CSS spinner while loading locks content

core/src/main/javascript/google/registry/ui/css/registry-lock.css

@@ -45,3 +45,41 @@
  .lock-confirm-modal button {
    margin-left: 10px
  }
+
+/** Following section taken from https://loading.io/css, under CC0 licensing. */
+.lds-ring {
+  display: inline-block;
+  position: relative;
+  width: 80px;
+  height: 80px;
+}
+.lds-ring div {
+  box-sizing: border-box;
+  display: block;
+  position: absolute;
+  width: 64px;
+  height: 64px;
+  margin: 8px;
+  border: 8px solid #000000;
+  border-radius: 50%;
+  animation: lds-ring 1.2s cubic-bezier(0.5, 0, 0.5, 1) infinite;
+  border-color: #000000 transparent transparent transparent;
+}
+.lds-ring div:nth-child(1) {
+  animation-delay: -0.45s;
+}
+.lds-ring div:nth-child(2) {
+  animation-delay: -0.3s;
+}
+.lds-ring div:nth-child(3) {
+  animation-delay: -0.15s;
+}
+@keyframes lds-ring {
+  0% {
+    transform: rotate(0deg);
+  }
+  100% {
+    transform: rotate(360deg);
+  }
+}
+/** End of material taken from https://loading.io/css. */

core/src/main/resources/google/registry/ui/soy/registrar/RegistryLock.soy

@@ -18,7 +18,15 @@
 {template .settings}
   <h1>Registry lock</h1>
   <br>
-  <div id="locks-content"></div>
+  <div id="locks-content">
+    // CSS-ified loading spinner
+    <div class="{css('lds-ring')}">
+      <div></div>
+      <div></div>
+      <div></div>
+      <div></div>
+    </div>
+  </div>
 {/template}
 
 {template .locksContent}