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

third_party/WebKit/Source/modules/media_controls/MediaDownloadInProductHelpManager.cpp

+// 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.
+
+#include "modules/media_controls/MediaDownloadInProductHelpManager.h"
+
+#include "core/frame/LocalFrameClient.h"
+#include "modules/media_controls/MediaControlsImpl.h"
+#include "modules/media_controls/elements/MediaControlDownloadButtonElement.h"
+#include "services/service_manager/public/cpp/interface_provider.h"
+
+namespace blink {
+
+MediaDownloadInProductHelpManager::MediaDownloadInProductHelpManager(
+    MediaControlsImpl& controls)
+    : controls_(controls) {}
+
+MediaDownloadInProductHelpManager::~MediaDownloadInProductHelpManager() =
+    default;
+
+void MediaDownloadInProductHelpManager::SetControlsState(bool can_show) {
+  if (controls_can_show_ == can_show)
+    return;
+
+  controls_can_show_ = can_show;
+  StateUpdated();
+}
+
+void MediaDownloadInProductHelpManager::SetDownloadButtonState(bool can_show) {
+  if (button_can_show_ == can_show)
+    return;
+
+  button_can_show_ = can_show;
+  StateUpdated();
+}
+
+void MediaDownloadInProductHelpManager::SetPlayState(bool is_playing) {
+  if (is_playing_ == is_playing)
+    return;
+
+  is_playing_ = is_playing;
+  StateUpdated();
+}
+
+bool MediaDownloadInProductHelpManager::IsShowingInProductHelp() const {
+  return !!media_in_product_help_;
+}
+
+void MediaDownloadInProductHelpManager::
+    MaybeDispatchDownloadInProductHelpTrigger() {
+  // Only show in-product-help once for an element.
+  if (media_download_in_product_trigger_observed_)
+    return;
+
+  auto* frame = controls_->GetDocument().GetFrame();
+  if (!frame)
+    return;
+
+  // If the button is not in the viewport, don't show the in-product-help.
+  IntRect button_rect =
+      controls_->DownloadButton().VisibleBoundsInVisualViewport();
+  if (button_rect.IsEmpty())

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

What if it is partially hidden?

[Khushal, 2017/08/16 19:01:22]

That's a good point. I could look at button size and compare it with the rect to
see if its clipped. But I think this case should be rare.

For the hidden case, I was seeing instances where we would position the widget
at the origin in the browser because the rect was empty.

+    return;
+
+  media_download_in_product_trigger_observed_ = true;
+  media_in_product_help_ =
+      WTF::MakeUnique<mojom::blink::MediaDownloadInProductHelpPtr>();
+  frame->Client()->GetInterfaceProvider()->GetInterface(
+      mojo::MakeRequest(media_in_product_help_.get()));
+  media_in_product_help_->set_connection_error_handler(ConvertToBaseCallback(
+      WTF::Bind(&MediaDownloadInProductHelpManager::DismissInProductHelp,
+                WrapWeakPersistent(this))));
+
+  // MaybeShow should always make the controls visible since we early out if
+  // CanShow is false for the controls.
+  controls_->MaybeShow();
+  (*media_in_product_help_)->ShowInProductHelpWidget(button_rect);
+}
+
+void MediaDownloadInProductHelpManager::StateUpdated() {
+  if (CanShowInProductHelp())
+    MaybeDispatchDownloadInProductHelpTrigger();
+  else
+    DismissInProductHelp();
+}
+
+bool MediaDownloadInProductHelpManager::CanShowInProductHelp() const {
+  // If showing the controls is disabled, we can't make them visible to show the
+  // in-product-help.
+  if (!controls_can_show_)
+    return false;
+
+  // If the download option is not available for this video, no need to show
+  // anything.
+  if (!button_can_show_)
+    return false;
+
+  // Restrict showing in-product-help to when the video is playing.
+  if (!is_playing_)
+    return false;

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

You might want to merge this into one `return controls_can_show_ &&
button_con_show_ && is_playing_;` with a big comment above.

[Khushal, 2017/08/16 19:01:22]

Done.

+
+  return true;
+}
+
+void MediaDownloadInProductHelpManager::DismissInProductHelp() {
+  if (!media_in_product_help_)
+    return;
+
+  media_in_product_help_.reset();
+  controls_->DidDismissDownloadInProductHelp();
+}
+
+DEFINE_TRACE(MediaDownloadInProductHelpManager) {
+  visitor->Trace(controls_);
+}
+
+}  // namespace blink