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 "core/html/shadow/MediaControlElementTypes.h"
+#include "public/platform/media_in_product_help.mojom-blink.h"
 
 namespace blink {
 
 class Event;
 class MediaControlsImpl;
 
 class MediaControlDownloadButtonElement final
     : 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();
 
+  void UpdateInProductHelpState();
+  void MaybeDispatchInProductHelpTrigger();
+  bool IsShowingInProductHelp() const;
+
   // MediaControlInputElement overrides.
   // TODO(mlamouri): add WillRespondToMouseClickEvents
   WebLocalizedString::Name GetOverflowStringName() override;
   bool HasOverflowButton() override;
   void SetIsWanted(bool) override;
 
   DECLARE_VIRTUAL_TRACE();
 
  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*) override;
 
   void RecordMetrics(DownloadActionMetrics);
+  void DismissDownloadInProductHelp();
 
   // Points to an anchor element that contains the URL of the media file.
   Member<HTMLAnchorElement> anchor_;
 
   // UMA related boolean. They are used to prevent counting something twice
   // for the same media element.
   bool click_use_counted_ = false;
   bool show_use_counted_ = false;
+
+  std::unique_ptr<mojom::blink::MediaInProductHelpPtr> media_in_product_help_;
+  bool media_download_in_product_trigger_observed_ = false;
 };
 
 }  // namespace blink
 
 #endif  // MediaControlDownloadButtonElement_h