DevTools -> Memory Tab -> Allowing to edit a title of a heap snapshot

third_party/WebKit/Source/devtools/front_end/profiler/HeapSnapshotView.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 233 matching lines @@
 
   /**
    * @override
    * @return {!Array<!UI.ToolbarItem>}
    */
   syncToolbarItems() {
     var result = [this._perspectiveSelect, this._classNameFilter];
     if (this._profile.profileType() !== Profiler.ProfileTypeRegistry.instance.trackingHeapSnapshotProfileType)
       result.push(this._baseSelect, this._filterSelect);
     result.push(this._selectedSizeText);
+    this._updateControls();

[alph, 2017/07/11 18:44:23]

Oh, got it. Thanks!

So the title updates for older profiles do not come to the HeapSnapshotView's
created later, as they do not subscribe to these (because the newer views do not
get _onReceiveSnapshot called for already existing snapshots). This is a bit
awkward that a view have listeners for title change for newer profiles, but not
for older ones. I see two options to make it consistent:

1.
Keep this _updateControls call, but remove the listener for title change on the
view for foreign profiles. E.g add a check: if (profile == this._profile)
profile.addEventlistener(...);
to the _onReceiveSnapshot

2.
Remove this _updateControls call, and add something like:

for (var existingProfile of this._profiles()) {
  existingProfile.addEventListener(
      Profiler.ProfileHeader.Events.ProfileTitleChanged, this._updateControls,
this);
}

to the HeapSnapshotView constructor. To make sure the view subscribes to title
change for all the profiles.

[diana.suvorova, 2017/07/11 19:19:53]

I see. This makes sense.  I went with option #2.

     return result;
   }
 
   /**
    * @override
    */
   willHide() {
     this._currentSearchResultIndex = -1;
     this._popoverHelper.hidePopover();
   }
@@ skipping 336 matching lines @@
     const multipleSnapshots = this._profiles().length > 1;
     this._perspectiveSelect.removeOptions();
     this._perspectives.forEach((perspective, index) => {
       if (multipleSnapshots || perspective !== this._comparisonPerspective)
         this._perspectiveSelect.createOption(perspective.title(), '', String(index));
     });
   }
 
   _updateBaseOptions() {
     var list = this._profiles();
-    // We're assuming that snapshots can only be added.
-    if (this._baseSelect.size() === list.length)
-      return;
+    var selectedIndex = this._baseSelect.selectedIndex();
 
-    for (var i = this._baseSelect.size(), n = list.length; i < n; ++i) {
-      var title = list[i].title;
-      this._baseSelect.createOption(title);
-    }
+    this._baseSelect.removeOptions();
+    for (var item of list)
+      this._baseSelect.createOption(item.title);
+
+    if (selectedIndex > -1)
+      this._baseSelect.setSelectedIndex(selectedIndex);
   }
 
   _updateFilterOptions() {
     var list = this._profiles();
-    // We're assuming that snapshots can only be added.
-    if (this._filterSelect.size() - 1 === list.length)
-      return;
+    var selectedIndex = this._filterSelect.selectedIndex();
 
-    if (!this._filterSelect.size())
-      this._filterSelect.createOption(Common.UIString('All objects'));
-
-    for (var i = this._filterSelect.size() - 1, n = list.length; i < n; ++i) {
-      var title = list[i].title;
+    this._filterSelect.removeOptions();
+    this._filterSelect.createOption(Common.UIString('All objects'));
+    for (var i = 0; i < list.length; ++i) {
+      var title;
       if (!i)
-        title = Common.UIString('Objects allocated before %s', title);
+        title = Common.UIString('Objects allocated before %s', list[i].title);
       else
-        title = Common.UIString('Objects allocated between %s and %s', list[i - 1].title, title);
+        title = Common.UIString('Objects allocated between %s and %s', list[i - 1].title, list[i].title);
       this._filterSelect.createOption(title);
     }
+
+    if (selectedIndex > -1)
+      this._filterSelect.setSelectedIndex(selectedIndex);
   }
 
   _updateControls() {
     this._updatePerspectiveOptions();
     this._updateBaseOptions();
     this._updateFilterOptions();
   }
 
   /**
    * @param {!Common.Event} event
    */
   _onReceiveSnapshot(event) {
     this._updateControls();
+    var profile = event.data;
+    profile.addEventListener(Profiler.ProfileHeader.Events.ProfileTitleChanged, this._updateControls, this);
   }
 
   /**
    * @param {!Common.Event} event
    */
   _onProfileHeaderRemoved(event) {
     var profile = event.data;
+    profile.removeEventListener(Profiler.ProfileHeader.Events.ProfileTitleChanged, this._updateControls, this);
+
     if (this._profile === profile) {
       this.detach();
       this._profile.profileType().removeEventListener(
           Profiler.HeapSnapshotProfileType.SnapshotReceived, this._onReceiveSnapshot, this);
       this._profile.profileType().removeEventListener(
           Profiler.ProfileType.Events.RemoveProfileHeader, this._onProfileHeaderRemoved, this);
       this.dispose();
     } else {
       this._updateControls();
     }
@@ skipping 1307 matching lines @@
           frame.line - 1, frame.column - 1);
       frameDiv.appendChild(urlElement);
     }
   }
 
   clear() {
     this.element.removeChildren();
     this._linkifier.reset();
   }
 };