Gallery.app: Make the window header work.

* Adds the headers of the maximze, minimize, and close buttons.
* Turn the header to a draggable region.

BUG=358698
TEST=manually

Review URL: https://codereview.chromium.org/254203003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267493 0039d316-1c4b-4281-b951-d872f2087c98

ui/file_manager/gallery/css/gallery.css

@@ -178,6 +178,7 @@ body {
 }
 
 .gallery > .header {
+  -webkit-app-region: drag;
   -webkit-box-align: center;
   -webkit-box-pack: end;
   border-bottom: 1px solid rgba(50, 50, 50, 0.8);
@@ -186,6 +187,10 @@ body {
   top: 0;
 }
 
+.gallery .header button {
+  -webkit-app-region: no-drag;
+}
+
 .gallery > .toolbar {
   border-top: 1px solid rgba(50, 50, 50, 0.8);
   bottom: 0;

ui/file_manager/gallery/js/gallery.js

@@ -29,9 +29,15 @@ function Gallery(volumeManager) {
   this.context_ = {
     appWindow: chrome.app.window.current(),
     onBack: function() {},
-    onClose: function() {},
-    onMaximize: function() {},
-    onMinimize: function() {},
+    onClose: function() { close(); },
+    onMaximize: function() {
+      var appWindow = chrome.app.window.current();
+      if (appWindow.isMaximized())
+        appWindow.restore();
+      else
+        appWindow.maximize();
+    },
+    onMinimize: function() { chrome.app.window.current().minimize(); },
     onAppRegionChanged: function() {},
     metadataCache: MetadataCache.createFull(volumeManager),
     shareActions: [],