Disable autocap in settings search field.

Without this the VK will try to capitalise search strings in this field.
Since users aren't typing sentences here, this doesn't make sense.

Background: This broke some of our tast tests when I fixed the VK to make it autocap correctly, but after talking to PM, we shouldn't autocap this field.


BUG:b/175338193

Change-Id: I54c66bad1a571466d60b4804208ae6931d26cc0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2584724Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: John Palmer <jopalmer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835995}

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html

@@ -183,6 +183,7 @@
       <label id="prompt" for="searchInput" aria-hidden="true">[[label]]</label>
       <input id="searchInput"
           aria-labelledby="prompt"
+          autocapitalize="off"
           autocomplete="off"
           type="search"
           on-input="onSearchTermInput"