Enforce the 'requirements' field in manifests.

chrome/browser/extensions/requirements_checker.h

+// Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_CHECKER_H_
+#define CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_CHECKER_H_
+
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/extensions/extension_service.h"
+
+class GPUFeatureChecker;
+
+namespace extensions {
+class Extension;
+
+// This class lives on the UI  thread. This includes any calls to AsWeakPtr().

[Aaron Boodman, 2012/08/21 23:04:21]

extra space after "UI"

[Aaron Boodman, 2012/08/21 23:04:21]

Validates the 'requirements' extension manifest field. This is an asynchronous
process that involves several threads, but the public interface of this class
(including constructor and destructor) must only be used on the UI thread.

[eaugusti, 2012/08/24 19:30:52]

Done.

+class RequirementsChecker : public base::SupportsWeakPtr<RequirementsChecker> {
+ public:
+  RequirementsChecker();
+  ~RequirementsChecker();
+
+  // The vector passed to the callback are any localized errors describing
+  // requirement violations. If this vector is non-empty, requirements checking
+  // failed. This should only be called once. |callback| will always be invoked
+  // asynchronously on the UI thread.
+  void Check(scoped_refptr<const Extension> extension,
+      base::Callback<void(std::vector<std::string>)> callback);
+
+ private:
+  // Callbacks for the GPUFeatureChecker.
+  void SetWebGLAvailability(bool available);
+  void SetCSS3DAvailability(bool available);
+
+  void MaybeRunCallback();
+
+  std::vector<std::string> errors_;
+
+  // Every requirement that needs to be resolved asynchronously will add to
+  // this counter. When the counter is depleted, the callback will be run.
+  int pending_requirement_checks_;
+
+  scoped_refptr<GPUFeatureChecker> webgl_checker_;
+  scoped_refptr<GPUFeatureChecker> css3d_checker_;
+
+  base::Callback<void(std::vector<std::string>)> callback_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_CHECKER_H_