Disable the MD Clear Browsing Data dialog checkboxes during clearing

When clearing is in progress, we disable the buttons. We should also
disable the checkboxes.

Leaving them enabled not only gives the false impression that the
datatype selection is modifiable during clearing, it can also have
an undesired effect: When the clearing finishes, we show the message
about other forms of history based on whether the history checkbox was
checked - and thus we shouldn't allow (un)checking in.

https://screenshot.googleplex.com/0VXxxLtXHZU.png

BUG=595580
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2283853002
Cr-Commit-Position: refs/heads/master@{#414784}

chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.html

@@ -124,42 +124,50 @@
         <settings-checkbox id="browsingCheckbox"
             pref="{{prefs.browser.clear_data.browsing_history}}"
             label="$i18n{clearBrowsingHistory}"
-            sub-label="[[counters_.browsing_history]]">
+            sub-label="[[counters_.browsing_history]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox id="downloadCheckbox"
             pref="{{prefs.browser.clear_data.download_history}}"
             label="$i18n{clearDownloadHistory}"
-            sub-label="[[counters_.download_history]]">
+            sub-label="[[counters_.download_history]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.cache}}"
             label="$i18n{clearCache}"
-            sub-label="[[counters_.cache]]">
+            sub-label="[[counters_.cache]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.cookies}}"
             label="$i18n{clearCookies}"
-            sub-label="$i18n{clearCookiesCounter}">
+            sub-label="$i18n{clearCookiesCounter}"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.passwords}}"
             label="$i18n{clearPasswords}"
-            sub-label="[[counters_.passwords]]">
+            sub-label="[[counters_.passwords]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.form_data}}"
             label="$i18n{clearFormData}"
-            sub-label="[[counters_.form_data]]">
+            sub-label="[[counters_.form_data]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.hosted_apps_data}}"
             label="$i18n{clearHostedAppData}"
-            sub-label="[[counters_.hosted_apps_data]]">
+            sub-label="[[counters_.hosted_apps_data]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
         <settings-checkbox
             pref="{{prefs.browser.clear_data.media_licenses}}"
             label="$i18n{clearMediaLicenses}"
-            sub-label="[[counters_.media_licenses]]">
+            sub-label="[[counters_.media_licenses]]"
+            disabled="[[clearingInProgress_]]">
         </settings-checkbox>
       </div>
       <div class="button-container">