Introduce runtime.onSuspendCanceled() event.

chrome/browser/extensions/extension_process_manager.cc

Index: chrome/browser/extensions/extension_process_manager.cc
diff --git a/chrome/browser/extensions/extension_process_manager.cc b/chrome/browser/extensions/extension_process_manager.cc
index ac453d6182d0aec5ae03f332171aeadcec37c91a..06f4777a1e03b599a24683301864cafbb32bb5f6 100644
--- a/chrome/browser/extensions/extension_process_manager.cc
+++ b/chrome/browser/extensions/extension_process_manager.cc
@@ -112,9 +112,9 @@ struct ExtensionProcessManager::BackgroundPageData {
   int close_sequence_id;
 
   // True if the page responded to the ShouldUnload message and is currently
-  // dispatching the unload event. We use this to ignore any activity
-  // generated during the unload event that would otherwise keep the
-  // extension alive.
+  // dispatching the unload event. During this time any events that arrive will
+  // cancel the unload process and an onSuspendCanceled event will be dispatched
+  // to the page.
   bool is_closing;
 
   // Keeps track of when this page was last unloaded. Used for perf metrics.
@@ -442,6 +442,7 @@ int ExtensionProcessManager::DecrementLazyKeepaliveCount(
 
   return count;
 }
+
 void ExtensionProcessManager::IncrementLazyKeepaliveCountForView(
     RenderViewHost* render_view_host) {
   WebContents* web_contents =
@@ -456,6 +457,19 @@ void ExtensionProcessManager::IncrementLazyKeepaliveCountForView(
   }
 }
 
+void ExtensionProcessManager::CancelSuspend(
+     const Extension* extension) {
+  bool& is_closing = background_page_data_[extension->id()].is_closing;
+  if (is_closing) {
+    is_closing = false;

[Matt Perry, 2012/07/19 21:36:22]

Could you add a DCHECK that the lazy_keepalive_count is > 0 here? We should
enforce that the caller increments the keepalive count before cancelling the
suspend.

[koz (OOO until 15th September), 2012/07/20 06:08:09]

That's a good idea. In fact, it's probably a good idea to unify these two
methods, seeing as they need to be called in tandem. I've added an optional
cancel_suspend argument to IncrementLazyKeepaliveCount() that defaults to false.

+    OnLazyBackgroundPageActive(extension->id());
+    ExtensionHost* host = GetBackgroundHostForExtension(extension->id());
+    if (host)
+      host->render_view_host()->Send(
+          new ExtensionMsg_CancelUnload(extension->id()));
+  }
+}
+
 void ExtensionProcessManager::OnLazyBackgroundPageIdle(
     const std::string& extension_id, int sequence_id) {
   ExtensionHost* host = GetBackgroundHostForExtension(extension_id);
@@ -492,19 +506,24 @@ void ExtensionProcessManager::OnShouldUnloadAck(
 }
 
 void ExtensionProcessManager::OnUnloadAck(const std::string& extension_id) {
+  background_page_data_[extension_id].is_closing = true;
+  int sequence_id = background_page_data_[extension_id].close_sequence_id;
   MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&ExtensionProcessManager::CloseLazyBackgroundPageNow,
-                 weak_ptr_factory_.GetWeakPtr(), extension_id),
+                 weak_ptr_factory_.GetWeakPtr(), extension_id, sequence_id),
       event_page_unloading_time_);
 }
 
 void ExtensionProcessManager::CloseLazyBackgroundPageNow(
-    const std::string& extension_id) {
-  background_page_data_[extension_id].is_closing = true;
+    const std::string& extension_id, int sequence_id) {
   ExtensionHost* host = GetBackgroundHostForExtension(extension_id);
-  if (host)
-    CloseBackgroundHost(host);
+  if (host &&
+      sequence_id == background_page_data_[extension_id].close_sequence_id) {
+    ExtensionHost* host = GetBackgroundHostForExtension(extension_id);
+    if (host)
+      CloseBackgroundHost(host);
+  }
 }
 
 void ExtensionProcessManager::OnNetworkRequestStarted(