Reland: Refactor code that defers extension background page loading

src/extensions depends on chrome::NOTIFICATION_PROFILE_CREATED to support
deferred loading of extension background pages when the profile isn't ready
yet. This is a layering violation.

* Remove Chrome concepts like "browser window ready" and "profile created"
from ProcessManager. Introduce ProcessManagerDelegate with a general concept
of deferring background page loading.
* Consolidate all the tricky Chrome-specific background page loading rules into
ChromeProcessManagerDelegate. This keeps all the rules in one place. Annotate
each block of special case code with the bug that inspired it.
* Extend unit test coverage for ProcessManager.

This will make it easier to eliminate chrome::NOTIFICATION_PROFILE_DESTROYED
in ProcessManager in a later CL.

(Original CL https://codereview.chromium.org/381283002 broke valgrind bots
because it was initializing left-over BrowserContextKeyedServices from tests
running earlier in the same process.)

BUG=392658
TEST=unit_tests ProcessManagerTest, browser_tests ProcessManagerBrowserTest, manual

Review URL: https://codereview.chromium.org/408523005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284593 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 34 insertions, 0 deletions

diff --git a/extensions/browser/process_manager_delegate.h b/extensions/browser/process_manager_delegate.h
new file mode 100644
index 0000000..7cc48c0
--- /dev/null
+++ b/extensions/browser/process_manager_delegate.h
@@ -0,0 +1,34 @@
+// 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.
+
+#ifndef EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_
+#define EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_
+
+namespace content {
+class BrowserContext;
+};
+
+namespace extensions {
+
+// Customization of ProcessManager for the extension system embedder.
+class ProcessManagerDelegate {
+ public:
+  virtual ~ProcessManagerDelegate() {}
+
+  // Returns true if the embedder allows background pages for the given
+  // |context|.
+  virtual bool IsBackgroundPageAllowed(
+      content::BrowserContext* context) const = 0;
+
+  // Returns true if the embedder wishes to defer starting up the renderers for
+  // extension background pages. If the embedder returns true it must call
+  // ProcessManager::MaybeCreateStartupBackgroundHosts() when it is ready. See
+  // ChromeProcessManagerDelegate for examples of how this is useful.
+  virtual bool DeferCreatingStartupBackgroundHosts(
+      content::BrowserContext* context) const = 0;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_DELEGATE_H_