Bug 675539 - Make tab discard functionality work on tab objects direc…

…tly r=mconley

This removes the need to go through the browser-to-tab mapping when discarding
a tab and simplifies the relevant code. Besides being renamed discardBrowser()
was also split so that one can check if a tab can be discarded prior to trying
it.

Differential Revision: https://phabricator.services.mozilla.com/D20475

--HG--
extra : moz-landing-system : lando

browser/base/content/tabbrowser.js

@@ -2196,67 +2196,77 @@ window._gBrowser = {
     aTab.dispatchEvent(evt);
   },
 
-  discardBrowser(aBrowser, aForceDiscard) {
-    "use strict";
+  _mayDiscardBrowser(aTab, aForceDiscard) {
+    let browser = aTab.linkedBrowser;
+    let permitUnloadFlags = aForceDiscard ? browser.dontPromptAndUnload
+                                          : browser.dontPromptAndDontUnload;
 
-    let tab = this.getTabForBrowser(aBrowser);
+    if (!aTab ||
+        aTab.selected ||
+        aTab.closing ||
+        this._windowIsClosing ||
+        !browser.isConnected ||
+        !browser.isRemoteBrowser ||
+        !browser.permitUnload(permitUnloadFlags).permitUnload) {
+      return false;
+    }
 
-    let permitUnloadFlags = aForceDiscard ? aBrowser.dontPromptAndUnload : aBrowser.dontPromptAndDontUnload;
+    return true;
+  },
 
-    if (!tab ||
-        tab.selected ||
-        tab.closing ||
-        this._windowIsClosing ||
-        !aBrowser.isConnected ||
-        !aBrowser.isRemoteBrowser ||
-        !aBrowser.permitUnload(permitUnloadFlags).permitUnload) {
-      return;
+  discardBrowser(aTab, aForceDiscard) {
+    "use strict";
+    let browser = aTab.linkedBrowser;
+
+    if (!this._mayDiscardBrowser(aTab, aForceDiscard)) {
+      return false;
     }
 
     // Reset webrtc sharing state.
-    if (tab._sharingState) {
-      this.setBrowserSharing(aBrowser, {});
+    if (aTab._sharingState) {
+      this.setBrowserSharing(browser, {});
     }
-    webrtcUI.forgetStreamsFromBrowser(aBrowser);
+    webrtcUI.forgetStreamsFromBrowser(browser);
 
     // Set browser parameters for when browser is restored.  Also remove
     // listeners and set up lazy restore data in SessionStore. This must
-    // be done before aBrowser is destroyed and removed from the document.
-    tab._browserParams = {
-      uriIsAboutBlank: aBrowser.currentURI.spec == "about:blank",
-      remoteType: aBrowser.remoteType,
+    // be done before browser is destroyed and removed from the document.
+    aTab._browserParams = {
+      uriIsAboutBlank: browser.currentURI.spec == "about:blank",
+      remoteType: browser.remoteType,
       usingPreloadedContent: false,
     };
 
-    SessionStore.resetBrowserToLazyState(tab);
+    SessionStore.resetBrowserToLazyState(aTab);
 
-    this._outerWindowIDBrowserMap.delete(aBrowser.outerWindowID);
+    this._outerWindowIDBrowserMap.delete(browser.outerWindowID);
 
     // Remove the tab's filter and progress listener.
-    let filter = this._tabFilters.get(tab);
-    let listener = this._tabListeners.get(tab);
-    aBrowser.webProgress.removeProgressListener(filter);
+    let filter = this._tabFilters.get(aTab);
+    let listener = this._tabListeners.get(aTab);
+    browser.webProgress.removeProgressListener(filter);
     filter.removeProgressListener(listener);
     listener.destroy();
 
-    this._tabListeners.delete(tab);
-    this._tabFilters.delete(tab);
+    this._tabListeners.delete(aTab);
+    this._tabFilters.delete(aTab);
 
     // Reset the findbar and remove it if it is attached to the tab.
-    if (tab._findBar) {
-      tab._findBar.close(true);
-      tab._findBar.remove();
-      delete tab._findBar;
+    if (aTab._findBar) {
+      aTab._findBar.close(true);
+      aTab._findBar.remove();
+      delete aTab._findBar;
     }
 
-    aBrowser.destroy();
-    this.getPanel(aBrowser).remove();
-    tab.removeAttribute("linkedpanel");
+    browser.destroy();
+    this.getPanel(browser).remove();
+    aTab.removeAttribute("linkedpanel");
 
-    this._createLazyBrowser(tab);
+    this._createLazyBrowser(aTab);
 
     let evt = new CustomEvent("TabBrowserDiscarded", { bubbles: true });
-    tab.dispatchEvent(evt);
+    aTab.dispatchEvent(evt);
+    return true;
   },
 
   /**

browser/components/extensions/parent/ext-tabs.js

@@ -666,7 +666,7 @@ this.tabs = class extends ExtensionAPI {
 
         async discard(tabIds) {
           for (let nativeTab of getNativeTabsFromIDArray(tabIds)) {
-            nativeTab.ownerGlobal.gBrowser.discardBrowser(nativeTab.linkedBrowser);
+            nativeTab.ownerGlobal.gBrowser.discardBrowser(nativeTab);
           }
         },
 

browser/components/sessionstore/test/browser_1284886_suspend_tab.js

@@ -12,18 +12,18 @@ add_task(async function test() {
   let tab0 = gBrowser.tabs[0];
   let tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, url);
 
-  gBrowser.discardBrowser(tab0.linkedBrowser);
+  gBrowser.discardBrowser(tab0);
   ok(!tab0.linkedPanel, "tab0 is suspended");
 
   await BrowserTestUtils.switchTab(gBrowser, tab0);
 
   // Test that active tab is not able to be suspended.
-  gBrowser.discardBrowser(tab0.linkedBrowser);
+  gBrowser.discardBrowser(tab0);
   ok(tab0.linkedPanel, "active tab is not able to be suspended");
 
   // Test that tab that is closing is not able to be suspended.
   gBrowser._beginRemoveTab(tab1);
-  gBrowser.discardBrowser(tab1.linkedBrowser);
+  gBrowser.discardBrowser(tab1);
 
   ok(tab1.linkedPanel, "cannot suspend a tab that is closing");
 
@@ -32,27 +32,25 @@ add_task(async function test() {
   // Open tab containing a page which has a beforeunload handler which shows a prompt.
   url = "http://example.com/browser/browser/components/sessionstore/test/browser_1284886_suspend_tab.html";
   tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, url);
-  let browser1 = tab1.linkedBrowser;
   await BrowserTestUtils.switchTab(gBrowser, tab0);
 
   // Test that tab with beforeunload handler which would show a prompt cannot be suspended.
-  gBrowser.discardBrowser(browser1);
+  gBrowser.discardBrowser(tab1);
   ok(tab1.linkedPanel, "cannot suspend a tab with beforeunload handler which would show a prompt");
 
   // Test that tab with beforeunload handler which would show a prompt will be suspended if forced.
-  gBrowser.discardBrowser(browser1, true);
+  gBrowser.discardBrowser(tab1, true);
   ok(!tab1.linkedPanel, "force suspending a tab with beforeunload handler which would show a prompt");
 
   BrowserTestUtils.removeTab(tab1);
 
   // Open tab containing a page which has a beforeunload handler which does not show a prompt.
   url = "http://example.com/browser/browser/components/sessionstore/test/browser_1284886_suspend_tab_2.html";
   tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, url);
-  browser1 = tab1.linkedBrowser;
   await BrowserTestUtils.switchTab(gBrowser, tab0);
 
   // Test that tab with beforeunload handler which would not show a prompt can be suspended.
-  gBrowser.discardBrowser(browser1);
+  gBrowser.discardBrowser(tab1);
   ok(!tab1.linkedPanel, "can suspend a tab with beforeunload handler which would not show a prompt");
 
   BrowserTestUtils.removeTab(tab1);
@@ -64,7 +62,7 @@ add_task(async function test() {
   await BrowserTestUtils.switchTab(gBrowser, tab1);
   await BrowserTestUtils.switchTab(gBrowser, tab0);
 
-  gBrowser.discardBrowser(tab1.linkedBrowser);
+  gBrowser.discardBrowser(tab1);
   ok(tab1.linkedPanel, "cannot suspend a remote tab");
 
   BrowserTestUtils.removeTab(tab1);

testing/marionette/harness/marionette_harness/tests/unit/test_window_close_content.py

@@ -116,7 +116,7 @@ def test_close_browserless_tab(self):
               win.addEventListener("TabBrowserDiscarded", ev => {
                 arguments[0](true);
               }, { once: true});
-              win.gBrowser.discardBrowser(win.gBrowser.tabs[1].linkedBrowser);
+              win.gBrowser.discardBrowser(win.gBrowser.tabs[1]);
             """)
 
         window_handles = self.marionette.window_handles