Remove NOTIFICATION_EXTENSION_ENABLED.

chrome/browser/extensions/extension_service.cc

Index: chrome/browser/extensions/extension_service.cc
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 865438513dd39f0ea0d461506492a3c0736b8112..a77c73d51519aadb93502e5570341ec2dfc05351 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -79,6 +79,7 @@
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/external_install_info.h"
 #include "extensions/browser/install_flag.h"
+#include "extensions/browser/lazy_background_task_queue.h"
 #include "extensions/browser/renderer_startup_helper.h"
 #include "extensions/browser/runtime_data.h"
 #include "extensions/browser/uninstall_reason.h"
@@ -144,6 +145,8 @@ const int kUpdateIdleDelay = 5;
 // TODO(samuong): Remove this in M58 (see comment in ExtensionService::Init).
 const char kDeprecatedLoadComponentExtension[] = "load-component-extension";
 
+void DoNothingWithExtensionHost(extensions::ExtensionHost* host) {}
+
 }  // namespace
 
 // ExtensionService.
@@ -924,11 +927,7 @@ void ExtensionService::EnableExtension(const std::string& extension_id) {
 
   NotifyExtensionLoaded(extension);
 
-  // Notify listeners that the extension was enabled.
-  content::NotificationService::current()->Notify(
-      extensions::NOTIFICATION_EXTENSION_ENABLED,
-      content::Source<Profile>(profile_),
-      content::Details<const Extension>(extension));
+  MaybeSpinUpLazyBackgroundPage(extension);
 }
 
 void ExtensionService::DisableExtension(const std::string& extension_id,
@@ -2557,3 +2556,29 @@ void ExtensionService::OnInstalledExtensionsLoaded() {
 
   OnBlacklistUpdated();
 }
+
+void ExtensionService::MaybeSpinUpLazyBackgroundPage(
+    const Extension* extension) {
+  if (!extensions::BackgroundInfo::HasLazyBackgroundPage(extension))
+    return;
+
+  // For orphaned devtools, we will reconnect devtools to it later in
+  // DidCreateRenderViewForBackgroundPage().
+  OrphanedDevTools::iterator iter = orphaned_dev_tools_.find(extension->id());
+  bool has_orphaned_dev_tools = iter != orphaned_dev_tools_.end();
+
+  // Reloading component extension does not trigger install, so RuntimeAPI won't

[lazyboy, 2017/06/01 23:32:54]

This turns out to be interesting :)
Reloading component extension goes through a different code path and it won't
see OnExtensionWillBeInstalled when the extension is reloaded. I've tied the
logic of orphaned devtools with this.

[Devlin, 2017/06/02 01:57:28]

Fun!  So was this also a bug before?

This makes me wonder if this should be part of the LazyEventDispatchUtil, though
- wouldn't this be a problem for anything else that wants to run when an
extension is updated?  Is there a complication with moving this bit there?

[lazyboy, 2017/06/02 18:35:37]

It wasn't, because we used to call AddPendingTask on
NOTIFICATION_EXTENSION_ENABLED notification from EventRouter.
DriveFileSystemExtensionApiTest.RetainEntry luckily caught this.
I thought of putting the component extension logic in LazyEventDispatchUtil,
though we need to expose a public method in LazyEventDispatchUtil and call that
from here [1].
However, combining orphaned devtools isn't trivial, so I kept the change to
component extension here along with devtools logic. I can certainly do [1]
(which means we might call additional AddPendingTask if devtools is open, not a
big deal), let me know.

[Devlin, 2017/06/03 02:10:12]

Hmm, would we need to call it from here?  Couldn't the lazy event dispatch util
listen for OnExtensionLoaded +
Manifest::IsComponentLocation(extension->location())?
Correct me if I'm wrong, but calling multiple times should essentially be a
no-op, right?  Since the background page will already be active, and we don't do
anything with it.

[lazyboy, 2017/06/03 02:18:52]

OnExtensionLoaded can result from line 1583 as well (AddExtension), this one is
from EnableExtension. So just looking at OnExtensionLoaded wouldn't give us the
exact same behavior.
That's right.
Since the background page will already be active, and we don't do

[Devlin, 2017/06/05 15:38:38]

Oh, I see.  Drat.  This is fine, then.

[lazyboy, 2017/06/05 21:54:01]

Acknowledged.

+  // be able to detect its loading. Therefore, we need to spin up its lazy
+  // background page.
+  bool is_component_extension =
+      Manifest::IsComponentLocation(extension->location());
+
+  if (!has_orphaned_dev_tools && !is_component_extension)
+    return;
+
+  // Wake up the event page by posting a dummy task.
+  extensions::LazyBackgroundTaskQueue* queue =
+      extensions::LazyBackgroundTaskQueue::Get(profile_);
+  queue->AddPendingTask(profile_, extension->id(),
+                        base::Bind(&DoNothingWithExtensionHost));
+}