Make sure pages that are closing but not yet closed are still suspended (non-preferred approach).

third_party/WebKit/Source/core/page/Page.h

Index: third_party/WebKit/Source/core/page/Page.h
diff --git a/third_party/WebKit/Source/core/page/Page.h b/third_party/WebKit/Source/core/page/Page.h
index 69e603bfc81921b7e1cc668dbaa8ee6dc62ee935..fd7153753ccc42a99de856b6d443518f00cb7222 100644
--- a/third_party/WebKit/Source/core/page/Page.h
+++ b/third_party/WebKit/Source/core/page/Page.h
@@ -60,6 +60,7 @@ class Frame;
 class FrameHost;
 class PluginData;
 class PointerLockController;
+class ScopedPageSuspender;
 class ScrollingCoordinator;
 class Settings;
 class SpellCheckerClient;
@@ -187,10 +188,13 @@ class CORE_EXPORT Page final : public GarbageCollectedFinalized<Page>,
     return m_tabKeyCyclesThroughElements;
   }
 
-  // DefersLoading is used to delay loads during modal dialogs.
-  // Modal dialogs are supposed to freeze all background processes
-  // in the page, including prevent additional loads from staring/continuing.
-  void setSuspended(bool);
+  // Suspension is used to implement the "Optionally, pause while waiting for
+  // the user to acknowledge the message" step of simple dialog processing:
+  // https://html.spec.whatwg.org/multipage/webappapis.html#simple-dialogs
+  //
+  // Per https://html.spec.whatwg.org/multipage/webappapis.html#pause, no loads
+  // are allowed to start/continue in this state, and all background processing
+  // is also suspended.
   bool suspended() const { return m_suspended; }
 
   void setPageScaleFactor(float);
@@ -228,6 +232,8 @@ class CORE_EXPORT Page final : public GarbageCollectedFinalized<Page>,
   void willBeDestroyed();
 
  private:
+  friend class ScopedPageSuspender;
+
   explicit Page(PageClients&);
 
   void initGroup();
@@ -235,6 +241,10 @@ class CORE_EXPORT Page final : public GarbageCollectedFinalized<Page>,
   // SettingsDelegate overrides.
   void settingsChanged(SettingsDelegate::ChangeType) override;
 
+  // ScopedPageSuspender helpers.
+  void setSuspended(bool);
+  static PageSet& willBeClosedOrdinaryPages();
+
   Member<PageAnimator> m_animator;
   const Member<AutoscrollController> m_autoscrollController;
   Member<ChromeClient> m_chromeClient;