Add download button to MediaDocument on Android.

third_party/WebKit/Source/core/html/MediaDocument.cpp

 /*
  * Copyright (C) 2008 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/html/MediaDocument.h"
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "core/HTMLNames.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/RawDataDocumentParser.h"
+#include "core/dom/shadow/ShadowRoot.h"
+#include "core/events/Event.h"
+#include "core/events/EventListener.h"
 #include "core/events/KeyboardEvent.h"
 #include "core/frame/LocalFrame.h"
+#include "core/html/HTMLAnchorElement.h"
 #include "core/html/HTMLBodyElement.h"
+#include "core/html/HTMLContentElement.h"
+#include "core/html/HTMLDivElement.h"
 #include "core/html/HTMLHeadElement.h"
 #include "core/html/HTMLHtmlElement.h"
 #include "core/html/HTMLMetaElement.h"
 #include "core/html/HTMLSourceElement.h"
+#include "core/html/HTMLStyleElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "platform/Histogram.h"
 #include "platform/KeyboardCodes.h"
+#include "platform/text/PlatformLocale.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
+// Enums used for UMA histogram.
+enum MediaDocumentDownloadButtonValue {
+    MediaDocumentDownloadButtonShown,
+    MediaDocumentDownloadButtonClicked,
+    // Only append new enums here.
+    MediaDocumentDownloadButtonMax
+};
+
+void recordDownloadMetric(MediaDocumentDownloadButtonValue value)
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, mediaDocumentDownloadButtonHistogram, ("Blink.MediaDocument.DownloadButton", MediaDocumentDownloadButtonMax));
+    mediaDocumentDownloadButtonHistogram.count(value);
+}
+
 // FIXME: Share more code with PluginDocumentParser.
 class MediaDocumentParser : public RawDataDocumentParser {
 public:
     static RawPtr<MediaDocumentParser> create(MediaDocument* document)
     {
         return new MediaDocumentParser(document);
     }
 
 private:
     explicit MediaDocumentParser(Document* document)
         : RawDataDocumentParser(document)
         , m_didBuildDocumentStructure(false)
     {
     }
 
     void appendBytes(const char*, size_t) override;
 
     void createDocumentStructure();
 
     bool m_didBuildDocumentStructure;
 };
 
+class MediaDownloadEventListener final : public EventListener {
+public:
+    static RawPtr<MediaDownloadEventListener> create()
+    {
+        return new MediaDownloadEventListener();
+    }
+
+    bool operator==(const EventListener& other) const override
+    {
+        return this == &other;
+    }
+
+private:
+    MediaDownloadEventListener()
+        : EventListener(CPPEventListenerType)
+        , m_clicked(false)
+    {
+    }
+
+    void handleEvent(ExecutionContext* context, Event* event) override
+    {
+        if (!m_clicked) {
+            recordDownloadMetric(MediaDocumentDownloadButtonClicked);
+            m_clicked = true;
+        }
+    }
+
+    bool m_clicked;
+};
+
 void MediaDocumentParser::createDocumentStructure()
 {
     ASSERT(document());
     RawPtr<HTMLHtmlElement> rootElement = HTMLHtmlElement::create(*document());
     rootElement->insertedByParser();
     document()->appendChild(rootElement);
 
     document()->frame()->loader().dispatchDocumentElementAvailable();
     document()->frame()->loader().runScriptsAtDocumentElementAvailable();
     if (isDetached())
@@ skipping 12 matching lines @@
 
     RawPtr<HTMLSourceElement> source = HTMLSourceElement::create(*document());
     source->setSrc(document()->url());
 
     if (DocumentLoader* loader = document()->loader())
         source->setType(loader->responseMIMEType());
 
     media->appendChild(source.release());
 
     RawPtr<HTMLBodyElement> body = HTMLBodyElement::create(*document());
+    body->setAttribute(styleAttr, "margin: 0px;");
+
+    RawPtr<HTMLDivElement> div = HTMLDivElement::create(*document());
+    // Style sheets for media controls are lazily loaded until a media element is encountered.
+    // As a result, elements encountered before the media element will not get the right
+    // style at first if we put the styles in mediacontrols.css. To solve this issue, set the
+    // styles inline so that they will be applied when the page loads.
+    // See w3c example on how to centering an element: https://www.w3.org/Style/Examples/007/center.en.html
+    div->setAttribute(styleAttr,
+        "display: flex;"
+        "flex-direction: column;"
+        "justify-content: center;"
+        "align-items: center;"
+        "min-height: min-content;"
+        "height: 100%;");
+    RawPtr<HTMLContentElement> content = HTMLContentElement::create(*document());
+    div->appendChild(content.release());
+
+    if (RuntimeEnabledFeatures::mediaDocumentDownloadButtonEnabled()) {
+        RawPtr<HTMLAnchorElement> anchor = HTMLAnchorElement::create(*document());
+        anchor->setAttribute(downloadAttr, "");
+        anchor->setURL(document()->url());
+        anchor->setTextContent(document()->getCachedLocale(document()->contentLanguage()).queryString(WebLocalizedString::DownloadButtonLabel).upper());
+        // Using CSS style according to Android material design.
+        anchor->setAttribute(styleAttr,
+            "display: inline-block;"
+            "margin-top: 32px;"
+            "padding: 0 16px 0 16px;"
+            "height: 36px;"
+            "background: #4285F4;"
+            "font-family: Roboto;"
+            "font-size: 14px;"
+            "border-radius: 5px;"
+            "color: white;"
+            "font-weight: bold;"
+            "text-decoration: none;"
+            "min-width: 300px;"
+            "line-height: 36px;");
+        RawPtr<EventListener> listener = MediaDownloadEventListener::create();
+        anchor->addEventListener(EventTypeNames::click, listener, false);
+        RawPtr<HTMLDivElement> buttonContainer = HTMLDivElement::create(*document());
+        buttonContainer->setAttribute(styleAttr,
+            "position: absolute;"
+            "text-align: center;"
+            "left: 0;"
+            "right: 0;");
+        buttonContainer->appendChild(anchor.release());
+        div->appendChild(buttonContainer.release());
+        recordDownloadMetric(MediaDocumentDownloadButtonShown);
+    }
+
+    // According to https://html.spec.whatwg.org/multipage/browsers.html#read-media,
+    // MediaDocument should have a single child which is the video element. Use
+    // shadow root to hide all the elements we added here.
+    ShadowRoot& shadowRoot = body->ensureUserAgentShadowRoot();
+    shadowRoot.appendChild(div.release());
     body->appendChild(media.release());
-
     rootElement->appendChild(head.release());
     rootElement->appendChild(body.release());
 
     m_didBuildDocumentStructure = true;
 }
 
 void MediaDocumentParser::appendBytes(const char*, size_t)
 {
     if (m_didBuildDocumentStructure)
         return;
@@ skipping 32 matching lines @@
         KeyboardEvent* keyboardEvent = toKeyboardEvent(event);
         if (keyboardEvent->keyIdentifier() == "U+0020" || keyboardEvent->keyCode() == VKEY_MEDIA_PLAY_PAUSE) {
             // space or media key (play/pause)
             video->togglePlayState();
             event->setDefaultHandled();
         }
     }
 }
 
 } // namespace blink