Chrome OS: Sync settings screen should not have "Back" button.

Remove "Back" button after UI review.

Bug: 805505
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I95e343cd0e0626e39b2b8b3919ca5a773f25a2dc
Reviewed-on: https://chromium-review.googlesource.com/884436Reviewed-by: Wenzhao (Colin) Zang <wzang@chromium.org>
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531726}

chrome/browser/resources/chromeos/login/sync_consent.html

@@ -126,9 +126,7 @@
           [[i18nDynamic(locale, 'syncConsentSettingsStatusSyncAllOff')]]
         </div>
       </div>
-      <div class="bottom-buttons layout horizontal justified">
-        <oobe-back-button on-tap="onSettingsBack_">
-        </oobe-back-button>
+      <div class="bottom-buttons layout horizontal end-justified">
         <oobe-text-button inverse on-tap="onSettingsSaveAndContinue_">
           <div>
             [[i18nDynamic(locale, 'syncConsentSettingsSaveAndContinue')]]

chrome/browser/resources/chromeos/login/sync_consent.js

@@ -42,15 +42,6 @@ Polymer({
     return activeSectionName != thisSectionName;
   },
 
-  /**
-   * This is 'on-tap' event handler for 'Back' button of Settings section.
-   * @private
-   */
-  onSettingsBack_: function() {
-    this.activeSection_ = 'overview';
-    this.focus();
-  },
-
   /**
    * This updates link to 'Settings' section on locale change.
    * @param {string} locale The UI language used.