MD Downloads: track downloads in C++, dispatch discrete JS updates

chrome/browser/resources/md_downloads/action_service.js

Index: chrome/browser/resources/md_downloads/action_service.js
diff --git a/chrome/browser/resources/md_downloads/action_service.js b/chrome/browser/resources/md_downloads/action_service.js
index f984fe5a14614e3b853993e4dcaad33b70577641..70c5e59af948b83f9ccb65ea2f3976fab249d2bf 100644
--- a/chrome/browser/resources/md_downloads/action_service.js
+++ b/chrome/browser/resources/md_downloads/action_service.js
@@ -45,7 +45,7 @@ cr.define('downloads', function() {
      *     (i.e. has a non-empty search term).
      */
     isSearching: function() {
-      return this.searchText_.length > 0;
+      return (this.searchText_ || '').length > 0;

[asanka, 2015/11/24 22:08:22]

!!this.searchText_

or do you folks dislike that expression?

[Dan Beam, 2015/11/25 04:06:36]

Done.

     },
 
     /** Opens the current local destination for downloads. */
@@ -78,9 +78,16 @@ cr.define('downloads', function() {
 
       this.searchText_ = searchText;
 
-      // Split quoted terms (e.g., 'The "lazy" dog' => ['The', 'lazy', 'dog']).
+      /**
+       * @param {string} s
+       * @return {string} |s| without whitespace at the ends (trimmed).
+       */
       function trim(s) { return s.trim(); }
-      chrome.send('getDownloads', searchText.split(/"([^"]*)"/).map(trim));
+
+      // Split quoted terms (e.g., 'The "lazy" dog' => ['The', 'lazy', 'dog']).
+      var terms = searchText ? searchText.split(/"([^"]*)"/).map(trim) : [];

[dpapad, 2015/11/24 18:42:33]

Is it worth adding tests for the regular expression? This could be a unit_test
(no DOM), similar to
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/res....

[Dan Beam, 2015/11/25 04:06:36]

Done.

+
+      chrome.send('getDownloads', terms);
     },
 
     /**