MD Settings: Ignore whitespace only search queries.

chrome/browser/resources/settings/settings_ui/settings_ui.js

Index: chrome/browser/resources/settings/settings_ui/settings_ui.js
diff --git a/chrome/browser/resources/settings/settings_ui/settings_ui.js b/chrome/browser/resources/settings/settings_ui/settings_ui.js
index c2b378aca4c6ccec8608cb973dd4c4426cd55b3e..affd985e7fe567bb46e2415d33c9bf1421d4454a 100644
--- a/chrome/browser/resources/settings/settings_ui/settings_ui.js
+++ b/chrome/browser/resources/settings/settings_ui/settings_ui.js
@@ -131,14 +131,20 @@ Polymer({
    * @private
    */
   onSearchChanged_: function(e) {
-    var query = e.detail;

[Dan Beam, 2016/10/26 20:51:11]

i think this entire patch could be

- var query = e.detail;
+ var query = e.detail.trim();

[dpapad, 2016/11/03 21:00:11]

See latest patch for a very similar approach.

+    // Ignore query if it contains whitespace only.
+    // TODO(dpapad): Should this be done by cr_search_field_behavior instead?

[dpapad, 2016/10/25 23:38:41]

MD History would probably benefit by moving this logic in
cr_search_field_behavior. It will currently search for whitespace only strings
which seems useless, see http://imgur.com/a/zl1di (notice the odd URL encoded
spaces in the URL).

[Dan Beam, 2016/10/26 02:10:03]

can we just put the fix in a shared place?  downloads, history, and extensions
would all benefit

+    if (/^\s+$/.test(e.detail))

[dpapad, 2016/10/25 23:38:41]

FWIW, I looked into Downloads, specifically at [1]. Could not find enough
similarities to justify any re-use. For the MD Settings case, here we simply
need to determine whether to trigger a search or not (by adding the URL
parameter*), but no need to split to tokens. The more fine-grained input search
query processing happens at a different layer at [2].

[1]
https://cs.chromium.org/chromium/src/chrome/browser/resources/md_downloads/ac...
[2]
https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/search...

*Note that this CL depends on the search URLs CL
https://codereview.chromium.org/2449663002.

+      return;

[Dan Beam, 2016/10/26 20:51:11]

this code is wrong.  consider moving from ' a' to ' ' in the search term (i.e.
typing ' a' then pressing backspace).  you'd want that to change the query

[dpapad, 2016/11/03 21:00:11]

Addressed in latest patch.

+
+    var query = e.detail.trim();
 
-    // 'search-changed' event was fired only because the search box's value was
-    // updated to reflect the already existing search URL parameter, no need to
-    // navigate again.
     var existingQuery = settings.getQueryParameters().get('search') || '';
-    if (query == existingQuery)
+    if (query == existingQuery) {
+      // 'search-changed' event was fired only because the search box's value
+      // was updated to reflect the already existing search URL parameter, no
+      // need to navigate again.
       return;
+    }
 
     settings.navigateTo(
         settings.Route.BASIC,