[MD History] Make forward/backward work in grouped mode.

chrome/browser/resources/md_history/history_toolbar.html

Index: chrome/browser/resources/md_history/history_toolbar.html
diff --git a/chrome/browser/resources/md_history/history_toolbar.html b/chrome/browser/resources/md_history/history_toolbar.html
index ab29c0ccb892cb8897b6df9797e7fc5ee40cb66d..c56e8cb7c6a8052e2f88e2be3906764c7c1740c2 100644
--- a/chrome/browser/resources/md_history/history_toolbar.html
+++ b/chrome/browser/resources/md_history/history_toolbar.html
@@ -231,17 +231,26 @@
           <paper-tab value="2">$i18n{rangeMonth}</paper-tab>
         </paper-tabs>
         <div id="grouped-nav-container">
-          <span id="grouped-date">
+          <span id="grouped-date" hidden$="[[querying]]">

[tsergeant, 2016/11/11 02:34:27]

IMO, this hiding is unnecessary.

It just causes the date to flash in and out distractingly. Without it, the dates
for the old results should still display until the new results are ready. This
mirrors the behavior of the main view, where the old results show until the new
ones appear.

[calamity, 2016/11/22 06:44:56]

Done.

             {{getHistoryInterval_(queryStartTime, queryEndTime)}}
           </span>
-          <paper-icon-button icon="history:today" alt="$i18n{rangeToday}"
-              title="$i18n{rangeToday}"></paper-icon-button>
-          <paper-icon-button icon="history:chevron-left"
-              alt="$i18n{rangePrevious}" title="$i18n{rangePrevious}"
-              class="rtl-reversible"></paper-icon-button>
-          <paper-icon-button icon="cr:chevron-right"
-              alt="$i18n{rangeNext}" title="$i18n{rangeNext}"
-              class="rtl-reversible"></paper-icon-button>
+          <paper-icon-button id="today-button" icon="history:today"

[tsergeant, 2016/11/11 02:34:27]

Do these buttons actually need IDs?

[calamity, 2016/11/22 06:44:56]

Just for tests?

+              alt="$i18n{rangeToday}"
+              title="$i18n{rangeToday}"
+              on-tap="todayTapped_"

[tsergeant, 2016/11/11 02:34:27]

Nit: Follow naming style of onTodayTap_ here and below

[calamity, 2016/11/22 06:44:56]

Done.

+              disabled="[[isToday_(groupedOffset)]]"></paper-icon-button>
+          <paper-icon-button id="prev-button" icon="history:chevron-left"
+              alt="$i18n{rangePrevious}"
+              title="$i18n{rangePrevious}"
+              class="rtl-reversible"
+              on-tap="prevTapped_"
+              disabled="[[queryFinished]]"></paper-icon-button>
+          <paper-icon-button id="next-button" icon="cr:chevron-right"
+              alt="$i18n{rangeNext}"
+              title="$i18n{rangeNext}"
+              class="rtl-reversible"
+              on-tap="nextTapped_"
+              disabled="[[isToday_(groupedOffset)]]"></paper-icon-button>
         </div>
       </div>
     </template>