Add Generic Implementation of ClipboardRecentContent

components/open_from_clipboard/clipboard_recent_content.h

 // Copyright 2015 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 COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_H_
 #define COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/time/time.h"
-
-class GURL;
+#include "url/gurl.h"
 
 // Helper class returning an URL if the content of the clipboard can be turned
 // into an URL, and if it estimates that the content of the clipboard is not too
 // old.
 class ClipboardRecentContent {
  public:
   ClipboardRecentContent();
   virtual ~ClipboardRecentContent();
 
   // Returns the global instance of the ClipboardRecentContent singleton. This
   // method does *not* create the singleton and will return null if no instance
   // was registered via SetInstance().
   static ClipboardRecentContent* GetInstance();
 
   // Sets the global instance of ClipboardRecentContent singleton.
   static void SetInstance(ClipboardRecentContent* instance);
 
-  // Returns true if the clipboard contains a recent URL that has not been
-  // supressed, and copies it in |url|. Otherwise, returns false. |url| must not
-  // be null.
+  // Returns true if the clipboard contains a recent URL that is appropriate to
+  // be suggested and has not been supressed, and copies it in |url|.
+  // Otherwise, returns false. |url| must not be null.
   virtual bool GetRecentURLFromClipboard(GURL* url) = 0;
 
   // Returns how old the content of the clipboard is.
   virtual base::TimeDelta GetClipboardContentAge() const = 0;
 
   // Prevent GetRecentURLFromClipboard from returning anything until the
   // clipboard's content changed.
   virtual void SuppressClipboardContent() = 0;
 
+ protected:
+  // GetRecentURLFromClipboard() should never return a URL from a clipboard
+  // older than this.
+  const base::TimeDelta kMaximumAgeOfClipboard = base::TimeDelta::FromHours(3);
+
+  // Returns true if the URL is appropriate to be suggested.
+  static bool IsAppropriateSuggestion(const GURL& url);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ClipboardRecentContent);
 };
 
 #endif  // COMPONENTS_OPEN_FROM_CLIPBOARD_CLIPBOARD_RECENT_CONTENT_H_