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

third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp

Index: third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
diff --git a/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp b/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
index f7a9f8f05c581e16d097cdb60ff5599fbb36acc9..221f127733d9d431eb4339bdf47be9518201bb2e 100644
--- a/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
+++ b/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
@@ -13,6 +13,7 @@
 #include "core/html/media/HTMLMediaSource.h"
 #include "core/page/Page.h"
 #include "modules/media_controls/MediaControlsImpl.h"
+#include "modules/media_controls/MediaDownloadInProductHelpManager.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
@@ -93,6 +94,15 @@ const char* MediaControlDownloadButtonElement::GetNameForHistograms() const {
   return IsOverflowElement() ? "DownloadOverflowButton" : "DownloadButton";
 }
 
+void MediaControlDownloadButtonElement::UpdateShownState() {
+  MediaControlInputElement::UpdateShownState();
+
+  if (GetMediaControls().DownloadInProductHelp()) {
+    GetMediaControls().DownloadInProductHelp()->SetDownloadButtonVisibility(
+        IsWanted() && DoesFit());
+  }
+}
+
 void MediaControlDownloadButtonElement::DefaultEventHandler(Event* event) {
   const KURL& url = MediaElement().currentSrc();
   if (event->type() == EventTypeNames::click &&