Prevented default backspace handler in File Browser Gallery

chrome/browser/resources/file_manager/js/image_editor/gallery.js

Index: chrome/browser/resources/file_manager/js/image_editor/gallery.js
diff --git a/chrome/browser/resources/file_manager/js/image_editor/gallery.js b/chrome/browser/resources/file_manager/js/image_editor/gallery.js
index bc59ba1f6b349a90e5e3071cde46a1cc4e6b6898..a6059cb62ce86b24154664bba914afbd2838c2c9 100644
--- a/chrome/browser/resources/file_manager/js/image_editor/gallery.js
+++ b/chrome/browser/resources/file_manager/js/image_editor/gallery.js
@@ -575,7 +575,12 @@ Gallery.prototype.onKeyDown_ = function(event) {
   if (this.isEditing_() && this.editor_.onKeyDown(event))
     return;
 
-  switch (event.keyIdentifier) {
+  switch (util.getKeyModifiers(event) + event.keyIdentifier) {
+    case 'U+0008': // Backspace.
+      // The default handler would call history.back and close the Gallery.
+      event.preventDefault();
+      break;
+
     case 'U+001B':  // Escape
       if (this.isEditing_()) {
         this.onEdit_();
@@ -611,9 +616,8 @@ Gallery.prototype.onKeyDown_ = function(event) {
       this.ribbon_.selectLast();
       break;
 
-    case 'U+00DD':
-      if (event.ctrlKey)  // Ctrl+] (cryptic on purpose).
-        this.ribbon_.toggleDebugSlideshow();
+    case 'Ctrl-U+00DD':  // Ctrl+] (cryptic on purpose).
+      this.ribbon_.toggleDebugSlideshow();
       break;
   }
 };