Add a test helper class for ExtensionRegistry.

extensions/browser/extension_test_registry_observer.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "extensions/browser/extension_test_registry_observer.h"
+
+#include "base/run_loop.h"
+#include "extensions/browser/extension_registry.h"
+
+namespace extensions {
+
+class ExtensionTestRegistryObserver::Waiter {
+ public:
+  Waiter() : waiting_(false), observed_(false) {}
+
+  void Wait() {
+    if (observed_)
+      return;
+
+    waiting_ = true;
+    runner_->Run();
+  }
+
+  void OnObserved() {
+    observed_ = true;
+    if (waiting_) {
+      waiting_ = false;
+      runner_->Quit();
+    }
+  }
+
+ private:
+  bool waiting_;
+  bool observed_;
+  scoped_refptr<content::MessageLoopRunner> runner_;

[not at google - send to devlin, 2014/06/16 21:42:08]

Doesn't look like this is ever initialized? And when it is, you could use its
existence rather than |waiting_|.

[limasdf, 2014/06/17 17:20:55]

Exactly. Happy to remove |waiting_|.

+
+  DISALLOW_COPY_AND_ASSIGN(Waiter);
+};
+
+ExtensionTestRegistryObserver::ExtensionTestRegistryObserver(
+    ExtensionRegistry* registry)
+    : installed_waiter_(new Waiter()),
+      uninstalled_waiter_(new Waiter()),
+      extension_registry_observer_(this) {
+  extension_registry_observer_.Add(registry);
+}
+
+ExtensionTestRegistryObserver::~ExtensionTestRegistryObserver() {
+}
+
+void ExtensionTestRegistryObserver::WaitForAnyExtensionUninstalled() {
+  uninstalled_waiter_->Wait();
+}
+
+void ExtensionTestRegistryObserver::WaitForAnyExtensionWillBeInstalled() {
+  installed_waiter_->Wait();
+}
+
+void ExtensionTestRegistryObserver::OnExtensionWillBeInstalled(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    bool is_update,
+    bool from_ephemeral,
+    const std::string& old_name) {
+  installed_waiter_->OnObserved();
+}
+
+void ExtensionTestRegistryObserver::OnExtensionUninstalled(
+    content::BrowserContext* browser_context,
+    const Extension* extension) {
+  uninstalled_waiter_->OnObserved();
+}
+
+}  // namespace extensions