Move ChromeRequirementsChecker to //extensions as a PreloadCheck

extensions/browser/preload_check.h

 // Copyright 2017 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_PRELOAD_CHECK_H_
 #define EXTENSIONS_BROWSER_PRELOAD_CHECK_H_
 
 #include <set>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 
 namespace extensions {
 
 class Extension;
 
 // Encapsulates a possibly asynchronous operation to verify whether a
 // precondition holds for loading the given extension.
 class PreloadCheck {
  public:
   // These enumerators should only be referred to by name, so it is safe to
   // insert or remove values as necessary.
   enum Error {
     NONE,
     BLACKLISTED_ID,
     BLACKLISTED_UNKNOWN,
     DISALLOWED_BY_POLICY,
+    NPAPI_NOT_SUPPORTED,
+    WEBGL_NOT_SUPPORTED,
+    WINDOW_SHAPE_NOT_SUPPORTED,
   };
 
   using Errors = std::set<Error>;
   using ResultCallback = base::OnceCallback<void(Errors)>;
 
   explicit PreloadCheck(scoped_refptr<const Extension> extension);
   virtual ~PreloadCheck();
 
   // This function must be called on the UI thread. The callback also occurs on
   // the UI thread.
   virtual void Start(ResultCallback callback) = 0;
 
   // Subclasses may provide an error message.
   virtual base::string16 GetErrorMessage() const;
 
   const Extension* extension() { return extension_.get(); }
 
  private:
   // The extension to check.
   scoped_refptr<const Extension> extension_;
 
   DISALLOW_COPY_AND_ASSIGN(PreloadCheck);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_PRELOAD_CHECK_H_