feat(extensions): expose ExtensionRegistryObserver events in Session

docs/api/session.md

@@ -91,6 +91,40 @@ session.defaultSession.on('will-download', (event, item, webContents) => {
 })
 ```
 
+#### Event: 'extension-loaded'
+
+Returns:
+
+* `event` Event
+* `extension` [Extension](structures/extension.md)
+
+Emitted after an extension is loaded. This occurs whenever an extension is
+added to the "enabled" set of extensions. This includes:
+- Extensions being loaded from `Session.loadExtension`.
+- Extensions being reloaded:
+   * from a crash.
+   * if the extension requested it ([`chrome.runtime.reload()`](https://developer.chrome.com/extensions/runtime#method-reload)).
+
+#### Event: 'extension-unloaded'
+
+Returns:
+
+* `event` Event
+* `extension` [Extension](structures/extension.md)
+
+Emitted after an extension is unloaded. This occurs when
+`Session.removeExtension` is called.
+
+#### Event: 'extension-ready'
+
+Returns:
+
+* `event` Event
+* `extension` [Extension](structures/extension.md)
+
+Emitted after an extension is loaded and all necessary browser state is
+initialized to support the start of the extension's background page.
+
 #### Event: 'preconnect'
 
 Returns:

shell/browser/api/electron_api_session.cc

@@ -281,6 +281,10 @@ Session::Session(v8::Isolate* isolate, ElectronBrowserContext* browser_context)
     service->SetHunspellObserver(this);
   }
 #endif
+
+#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
+  extensions::ExtensionRegistry::Get(browser_context)->AddObserver(this);
+#endif
 }
 
 Session::~Session() {
@@ -294,6 +298,10 @@ Session::~Session() {
     service->SetHunspellObserver(nullptr);
   }
 #endif
+
+#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
+  extensions::ExtensionRegistry::Get(browser_context())->RemoveObserver(this);
+#endif
 }
 
 void Session::OnDownloadCreated(content::DownloadManager* manager,
@@ -749,6 +757,22 @@ v8::Local<v8::Value> Session::GetAllExtensions() {
   }
   return gin::ConvertToV8(v8::Isolate::GetCurrent(), extensions_vector);
 }
+
+void Session::OnExtensionLoaded(content::BrowserContext* browser_context,
+                                const extensions::Extension* extension) {
+  Emit("extension-loaded", extension);
+}
+
+void Session::OnExtensionUnloaded(content::BrowserContext* browser_context,
+                                  const extensions::Extension* extension,
+                                  extensions::UnloadedExtensionReason reason) {
+  Emit("extension-unloaded", extension);
+}
+
+void Session::OnExtensionReady(content::BrowserContext* browser_context,
+                               const extensions::Extension* extension) {
+  Emit("extension-ready", extension);
+}
 #endif
 
 v8::Local<v8::Value> Session::Cookies(v8::Isolate* isolate) {

shell/browser/api/electron_api_session.h

@@ -25,6 +25,11 @@
 #include "chrome/browser/spellchecker/spellcheck_hunspell_dictionary.h"  // nogncheck
 #endif
 
+#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extension_registry_observer.h"
+#endif
+
 class GURL;
 
 namespace base {
@@ -55,6 +60,9 @@ class Session : public gin::Wrappable<Session>,
                 public gin_helper::CleanedUpAtExit,
 #if BUILDFLAG(ENABLE_BUILTIN_SPELLCHECKER)
                 public SpellcheckHunspellDictionary::Observer,
+#endif
+#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
+                public extensions::ExtensionRegistryObserver,
 #endif
                 public content::DownloadManager::Observer {
  public:
@@ -126,6 +134,15 @@ class Session : public gin::Wrappable<Session>,
   void RemoveExtension(const std::string& extension_id);
   v8::Local<v8::Value> GetExtension(const std::string& extension_id);
   v8::Local<v8::Value> GetAllExtensions();
+
+  // extensions::ExtensionRegistryObserver:
+  void OnExtensionLoaded(content::BrowserContext* browser_context,
+                         const extensions::Extension* extension) override;
+  void OnExtensionReady(content::BrowserContext* browser_context,
+                        const extensions::Extension* extension) override;
+  void OnExtensionUnloaded(content::BrowserContext* browser_context,
+                           const extensions::Extension* extension,
+                           extensions::UnloadedExtensionReason reason) override;
 #endif
 
  protected:

spec-main/extensions-spec.ts

@@ -127,6 +127,23 @@ describe('chrome extensions', () => {
     }
   });
 
+  it('emits extension lifecycle events', async () => {
+    const customSession = session.fromPartition(`persist:${require('uuid').v4()}`);
+
+    const loadedPromise = emittedOnce(customSession, 'extension-loaded');
+    const extension = await customSession.loadExtension(path.join(fixtures, 'extensions', 'red-bg'));
+    const [, loadedExtension] = await loadedPromise;
+    const [, readyExtension] = await emittedOnce(customSession, 'extension-ready');
+
+    expect(loadedExtension.id).to.equal(extension.id);
+    expect(readyExtension.id).to.equal(extension.id);
+
+    const unloadedPromise = emittedOnce(customSession, 'extension-unloaded');
+    await customSession.removeExtension(extension.id);
+    const [, unloadedExtension] = await unloadedPromise;
+    expect(unloadedExtension.id).to.equal(extension.id);
+  });
+
   it('lists loaded extensions in getAllExtensions', async () => {
     const customSession = session.fromPartition(`persist:${require('uuid').v4()}`);
     const e = await customSession.loadExtension(path.join(fixtures, 'extensions', 'red-bg'));