cros: Replace custom header for wallpaper picker with default.

Currently the wallpaper picker uses a customer header that lacks a
maximize button. However, the wallpaper picker is resizeable and can be
maximized. To make the wallpaper picker consistent with similar apps,
replaced custom header with the default.

Test: manual
Bug: 1096274
Change-Id: If7d31b2ef53c782b05d361b8147554736742726f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316152Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Jeremy Chinsen <chinsenj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791553}

chrome/browser/resources/chromeos/wallpaper_manager/css/wallpaper_manager.css

@@ -336,11 +336,6 @@ body:not([surprise-me-disabled]) [visibleif~='surprise-me-disabled'] {
   content: url(../images/ui/remember.png);
 }
 
-#dialog-header {
-  display: flex;
-  height: 40px;
-}
-
 .dialog-body {
   display: flex;
   height: 100%;
@@ -388,31 +383,6 @@ body:not([surprise-me-disabled]) [visibleif~='surprise-me-disabled'] {
   display: block;
 }
 
-#dialog-header > div {
-  -webkit-app-region: no-drag;
-  border-radius: 50%;
-  display: block;
-  height: 24px;
-  position: absolute;
-  top: 4px;
-  transition: background-color 100ms;
-  width: 24px;
-}
-
-#dialog-header div:hover {
-  background-color: rgb(241, 243, 244);
-}
-
-#minimize-button {
-  background-image: url(../images/ui/ic_minimize_grey-1x.svg);
-  right: 32px;
-}
-
-#close-button {
-  background-image: url(../images/ui/ic_close_grey-1x.svg);
-  right: 4px;
-}
-
 #top-header {
   -webkit-app-region: no-drag;
   background-color: #fff;

chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js

@@ -194,10 +194,8 @@ chrome.app.runtime.onLaunched.addListener(function() {
   }
 
   var options = {
-    frame: 'none',
     innerBounds: {width: 768, height: 512, minWidth: 768, minHeight: 512},
     resizable: true,
-    alphaEnabled: true
   };
 
   chrome.app.window.create('main.html', options, function(window) {

chrome/browser/resources/chromeos/wallpaper_manager/js/wallpaper_manager.js

@@ -381,12 +381,6 @@ WallpaperManager.prototype.preDownloadDomInit_ = function() {
       'resize', this.onResize_.bind(this));
   this.document_.defaultView.addEventListener(
       'keydown', this.onKeyDown_.bind(this));
-  $('minimize-button').addEventListener('click', function() {
-    chrome.app.window.current().minimize();
-  });
-  $('close-button').addEventListener('click', function() {
-    window.close();
-  });
   window.addEventListener(Constants.WallpaperChangedBy3rdParty, e => {
     this.currentWallpaper_ = e.detail.wallpaperFileName;
     this.decorateCurrentWallpaperInfoBar_();

chrome/browser/resources/chromeos/wallpaper_manager/main.html

@@ -83,10 +83,6 @@ found in the LICENSE file.
     </div>
   </div>
   <div class="dialog-container">
-    <div id="dialog-header">
-      <div id="minimize-button"></div>
-      <div id="close-button"></div>
-    </div>
     <div class="dialog-body">
       <div class="dialog-topbar">
         <div id="navstrip">