Add a download button to the media player

third_party/WebKit/Source/core/html/shadow/MediaControlElements.h

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 197 matching lines @@
 public:
     static MediaControlOverflowMenuListElement* create(MediaControls&);
 
 private:
     explicit MediaControlOverflowMenuListElement(MediaControls&);
 
     void defaultEventHandler(Event*) override;
 };
 
 // ----------------------------
+// Represents a button that allows users to download media if the file is
+// downloadable.
+class MediaControlDownloadButtonElement final : public MediaControlInputElement {
+public:
+    static MediaControlDownloadButtonElement* create(MediaControls&, Document*);
+
+    WebLocalizedString::Name getOverflowStringName() override;
+
+    // Returns true if the download button should be shown. We should
+    // show the button for only non-MSE, non-EME, and non-MediaStream content.
+    bool shouldDisplayDownloadButton();
+
+private:
+    explicit MediaControlDownloadButtonElement(MediaControls&);
+
+    void defaultEventHandler(Event*) override;
+};
 
 class MediaControlTimelineElement final : public MediaControlInputElement {
 public:
     static MediaControlTimelineElement* create(MediaControls&);
 
     bool willRespondToMouseClickEvents() override;
 
     // FIXME: An "earliest possible position" will be needed once that concept
     // is supported by HTMLMediaElement, see https://crbug.com/137275
     void setPosition(double);
@@ skipping 102 matching lines @@
 public:
     static MediaControlCurrentTimeDisplayElement* create(MediaControls&);
 
 private:
     explicit MediaControlCurrentTimeDisplayElement(MediaControls&);
 };
 
 } // namespace blink
 
 #endif // MediaControlElements_h