Reland: Refactor code that defers extension background page loading

extensions/browser/process_manager_delegate.h

Index: extensions/browser/process_manager_delegate.h
diff --git a/extensions/browser/process_manager_delegate.h b/extensions/browser/process_manager_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..4f3f635d52c57feb4dee071d3f2fab9e3e2ad480
--- /dev/null
+++ b/extensions/browser/process_manager_delegate.h
@@ -0,0 +1,34 @@
+// Copyright 2013 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_