[net-internals] Fix JS exception on stopping capturing while in Capture view

chrome/browser/resources/net_internals/tab_switcher_view.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Controller and View for switching between tabs.
  *
  * The View part of TabSwitcherView displays the contents of the currently
  * selected tab (only one tab can be active at a time).
  *
@@ skipping 13 matching lines @@
    *
    * @param {?Function} opt_onTabSwitched Optional callback to run when the
    *                    active tab changes. Called as
    *                    opt_onTabSwitched(oldTabId, newTabId).
    */
   function TabSwitcherView(opt_onTabSwitched) {
     assertFirstConstructorCall(TabSwitcherView);
 
     this.tabIdToView_ = {};
     this.tabIdToLink_ = {};
-    // Ordered list of views.
-    this.viewList_ = [];
+    // Map from tab id to the views link visiblity.
+    this.tabIdsLinkVisibility_ = new Map();
     this.activeTabId_ = null;
 
     this.onTabSwitched_ = opt_onTabSwitched;
 
     // The ideal width of the tab list.  If width is reduced below this, the
     // tab list will be shrunk, but it will be returned to this width once it
     // can be.
     this.tabListWidth_ = $(TAB_LIST_ID).offsetWidth;
 
     superClass.call(this);
@@ skipping 45 matching lines @@
      * @param {string} tabId The ID to refer to the tab by.
      * @param {!View} view The tab's actual contents.
      * @param {string} name The name for the menu item that selects the tab.
      */
     addTab: function(tabId, view, name, hash) {
       if (!tabId) {
         throw Error('Must specify a non-false tabId');
       }
 
       this.tabIdToView_[tabId] = view;
-      this.viewList_.push(view);
+      this.tabIdsLinkVisibility_.set(tabId, true);
 
       var node = addNodeWithText($(TAB_LIST_ID), 'a', name);
       node.href = hash;
       this.tabIdToLink_[tabId] = node;
       addNode($(TAB_LIST_ID), 'br');
 
       // Tab content views start off hidden.
       view.show(false);
 
       this.tabListWidth_ = $(TAB_LIST_ID).offsetWidth;
     },
 
     showTabLink: function(tabId, isVisible) {
       var wasActive = this.activeTabId_ == tabId;
 
       setNodeDisplay(this.tabIdToLink_[tabId], isVisible);
+      this.tabIdsLinkVisibility_.set(tabId, isVisible);
 
       if (wasActive && !isVisible) {
         // If the link for active tab is being hidden, then switch to the first
         // tab which is still visible.
-        for (var view in this.viewList_) {

[eroman, 2016/07/06 20:06:29]

I agree that the current code is quite wrong.

The problem with your proposed map from tabId --> visibility is the visibility
state is never updated in the map (whereas before it queried the underlying
View). At a minimum this is a layering issue.

Instead I think we can accomplish this using the existing tabIdToView map:

for (var curTabId in this.tabIdToView_) {
  var curView = thistabIdToView_[curTabId];
   if (curView.isVisible())
     this.switchToTab(curTabId);
     break;
}

-          if (view.isVisible())
-            this.switchToTab(option.value);
+        for (var [localTabId, enabled] of this.tabIdsLinkVisibility_) {
+          if (enabled) {
+            this.switchToTab(localTabId);
+            break;
+          }
         }
       }
     },
 
     getAllTabViews: function() {
       return this.tabIdToView_;
     },
 
     getTabView: function(tabId) {
       return this.tabIdToView_[tabId];
@@ skipping 33 matching lines @@
 
       newView.show(this.isVisible());
 
       if (this.onTabSwitched_)
         this.onTabSwitched_(oldTabId, tabId);
     },
   };
 
   return TabSwitcherView;
 })();