Cookie controls toggle space reserving

Reserve space for (lazy-loaded) cookie controls toggle

Bug: 967668
Change-Id: Ia6fa8e84590c8512fcd6cb84f72f7db339b69e56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865222
Commit-Queue: Huanzhong Huang <huanzhong@chromium.org>
Reviewed-by: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707297}

chrome/browser/resources/ntp4/incognito_tab.css

@@ -124,6 +124,10 @@ em {
   flex: none;
 }
 
+#cookie-controls-toggle:not(:defined) {
+  width: 34px;
+}
+
 /** Layout ------------------------------------------------------------------ */
 
 /* Align the content, icon, and title to to the center. */