chrome/blink: Add functionality for in-product help for media elements.

third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.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 MediaControlDownloadButtonElement_h
 #define MediaControlDownloadButtonElement_h
 
+#include "modules/ModulesExport.h"
 #include "modules/media_controls/elements/MediaControlInputElement.h"
 
 namespace blink {
 
 class Event;
 class MediaControlsImpl;
 
-class MediaControlDownloadButtonElement final
+class MODULES_EXPORT MediaControlDownloadButtonElement final

[mlamouri (slow - plz ping), 2017/08/16 13:09:30]

Do you still need the export?

[Khushal, 2017/08/16 19:01:23]

The tests call SetIsWanted on the button to check that logic, so need the export
for that.

     : public MediaControlInputElement {
  public:
   explicit MediaControlDownloadButtonElement(MediaControlsImpl&);
 
   // 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();
 
   // MediaControlInputElement overrides.
   // TODO(mlamouri): add WillRespondToMouseClickEvents
   WebLocalizedString::Name GetOverflowStringName() const final;
   bool HasOverflowButton() const final;
 
   DECLARE_VIRTUAL_TRACE();
 
  protected:
   const char* GetNameForHistograms() const final;
+  void UpdateShownState() override;

[mlamouri (slow - plz ping), 2017/08/16 13:09:30]

Make it `final`?

[Khushal, 2017/08/16 19:01:23]

Done.

 
  private:
   // This is used for UMA histogram (Media.Controls.Download). New values should
   // be appended only and must be added before |Count|.
   enum class DownloadActionMetrics {
     kShown = 0,
     kClicked,
     kCount  // Keep last.
   };
 
   void DefaultEventHandler(Event*) final;
 
   // Points to an anchor element that contains the URL of the media file.
   Member<HTMLAnchorElement> anchor_;
 };
 
 }  // namespace blink
 
 #endif  // MediaControlDownloadButtonElement_h