ambient: add missing UI component.

Please see demo screenshot in the linked bug.

Bug: b/161481969
Test: covered by unittests.
Change-Id: I8e3d867220ff7e23e79ac807ce6929fd04a246ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342784
Commit-Queue: Meilin Wang <meilinw@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796884}

ash/BUILD.gn

@@ -198,6 +198,8 @@ component("ash") {
     "ambient/ui/assistant_response_container_view.h",
     "ambient/ui/glanceable_info_view.cc",
     "ambient/ui/glanceable_info_view.h",
+    "ambient/ui/media_string_view.cc",
+    "ambient/ui/media_string_view.h",
     "ambient/ui/photo_view.cc",
     "ambient/ui/photo_view.h",
     "ambient/util/ambient_util.cc",
@@ -1763,6 +1765,7 @@ test("ash_unittests") {
     "ambient/autotest_ambient_api_unittest.cc",
     "ambient/model/ambient_backend_model_unittest.cc",
     "ambient/ui/ambient_container_view_unittest.cc",
+    "ambient/ui/media_string_view_unittest.cc",
     "ambient/ui/photo_view_unittest.cc",
     "app_list/app_list_controller_impl_unittest.cc",
     "app_list/app_list_metrics_unittest.cc",

ash/ambient/test/ambient_ash_test_base.cc

@@ -12,6 +12,7 @@
 #include "ash/ambient/ambient_photo_controller.h"
 #include "ash/ambient/ui/ambient_background_image_view.h"
 #include "ash/ambient/ui/ambient_container_view.h"
+#include "ash/ambient/ui/media_string_view.h"
 #include "ash/ambient/ui/photo_view.h"
 #include "ash/assistant/ui/assistant_view_ids.h"
 #include "ash/public/cpp/ambient/fake_ambient_backend_controller_impl.h"
@@ -167,6 +168,22 @@ void AmbientAshTestBase::SetScreenBrightnessAndWait(double percent) {
   base::RunLoop().RunUntilIdle();
 }
 
+void AmbientAshTestBase::SimulateMediaMetadataChanged(
+    media_session::MediaMetadata metadata) {
+  GetMediaStringView()->MediaSessionMetadataChanged(metadata);
+}
+
+void AmbientAshTestBase::SimulateMediaPlaybackStateChanged(
+    media_session::mojom::MediaPlaybackState state) {
+  // Creates media session info.
+  media_session::mojom::MediaSessionInfoPtr session_info(
+      media_session::mojom::MediaSessionInfo::New());
+  session_info->playback_state = state;
+
+  // Simulate media session info changed.
+  GetMediaStringView()->MediaSessionInfoChanged(std::move(session_info));
+}
+
 void AmbientAshTestBase::SetPhotoViewImageSize(int width, int height) {
   auto* image_decoder = static_cast<TestAmbientImageDecoderImpl*>(
       ambient_controller()
@@ -182,6 +199,11 @@ AmbientAshTestBase::GetAmbientBackgroundImageView() {
       AssistantViewID::kAmbientBackgroundImageView));
 }
 
+MediaStringView* AmbientAshTestBase::GetMediaStringView() {
+  return static_cast<MediaStringView*>(
+      container_view()->GetViewByID(AssistantViewID::kAmbientMediaStringView));
+}
+
 void AmbientAshTestBase::FastForwardToInactivity() {
   task_environment()->FastForwardBy(
       2 * AmbientController::kAutoShowWaitTimeInterval);

ash/ambient/test/ambient_ash_test_base.h

@@ -15,12 +15,14 @@
 #include "ash/test/ash_test_base.h"
 #include "base/test/scoped_feature_list.h"
 #include "services/device/public/cpp/test/test_wake_lock_provider.h"
+#include "services/media_session/public/mojom/media_session.mojom.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 class AmbientContainerView;
 class AmbientPhotoController;
+class MediaStringView;
 
 // The base class to test the Ambient Mode in Ash.
 class AmbientAshTestBase : public AshTestBase {
@@ -66,6 +68,11 @@ class AmbientAshTestBase : public AshTestBase {
   // Simulates a screen brightness changed event.
   void SetScreenBrightnessAndWait(double percent);
 
+  void SimulateMediaMetadataChanged(media_session::MediaMetadata metadata);
+
+  void SimulateMediaPlaybackStateChanged(
+      media_session::mojom::MediaPlaybackState state);
+
   // Set the size of the next image that will be loaded.
   void SetPhotoViewImageSize(int width, int height);
 
@@ -86,6 +93,9 @@ class AmbientAshTestBase : public AshTestBase {
 
   AmbientBackgroundImageView* GetAmbientBackgroundImageView();
 
+  // Returns the media string view for displaying ongoing media info.
+  MediaStringView* GetMediaStringView();
+
   AmbientController* ambient_controller();
 
   AmbientPhotoController* photo_controller();

ash/ambient/ui/ambient_container_view.cc

@@ -10,6 +10,7 @@
 #include "ash/ambient/ui/ambient_assistant_container_view.h"
 #include "ash/ambient/ui/ambient_view_delegate.h"
 #include "ash/ambient/ui/glanceable_info_view.h"
+#include "ash/ambient/ui/media_string_view.h"
 #include "ash/ambient/ui/photo_view.h"
 #include "ash/ambient/util/ambient_util.h"
 #include "ash/assistant/ui/assistant_view_ids.h"
@@ -40,6 +41,7 @@ using chromeos::assistant::features::IsAmbientAssistantEnabled;
 constexpr int kHorizontalMarginDip = 16;
 constexpr int kVerticalMarginDip = 64;
 constexpr int kAssistantPreferredHeightDip = 128;
+constexpr int kMediaStringTopMarginDip = 25;
 
 // A tolerance threshold used to ignore spurious mouse move.
 constexpr int kMouseMoveErrorTolerancePx = 3;
@@ -132,6 +134,7 @@ void AmbientContainerView::Layout() {
   // Layout child views first to have proper bounds set for children.
   LayoutPhotoView();
   LayoutGlanceableInfoView();
+  LayoutMediaStringView();
   // The assistant view may not exist if |kAmbientAssistant| feature is
   // disabled.
   if (ambient_assistant_container_view_)
@@ -155,6 +158,9 @@ void AmbientContainerView::Init() {
   glanceable_info_view_ =
       AddChildView(std::make_unique<GlanceableInfoView>(delegate_));
 
+  media_string_view_ = AddChildView(std::make_unique<MediaStringView>());
+  media_string_view_->SetVisible(false);
+
   if (IsAmbientAssistantEnabled()) {
     ambient_assistant_container_view_ =
         AddChildView(std::make_unique<AmbientAssistantContainerView>());
@@ -187,6 +193,22 @@ void AmbientContainerView::LayoutAssistantView() {
       gfx::Rect(0, 0, preferred_width, preferred_height));
 }
 
+void AmbientContainerView::LayoutMediaStringView() {
+  const gfx::Size container_size = GetLocalBounds().size();
+  const gfx::Size preferred_size = media_string_view_->GetPreferredSize();
+
+  // The media string view is positioned on the right-top corner of the
+  // container.
+  // TODO(meilinw): without a maximum width limit, media string can grow too
+  // long or even overflow the screen. Revisit here to polish the UI once the
+  // spec is available. See b/163398805.
+  int x =
+      container_size.width() - kHorizontalMarginDip - preferred_size.width();
+  int y = kMediaStringTopMarginDip;
+  media_string_view_->SetBoundsRect(
+      gfx::Rect(x, y, preferred_size.width(), preferred_size.height()));
+}
+
 void AmbientContainerView::HandleEvent() {
   delegate_->OnBackgroundPhotoEvents();
 }

ash/ambient/ui/ambient_container_view.h

@@ -17,6 +17,7 @@ class AmbientAssistantContainerView;
 class AmbientViewDelegate;
 class GlanceableInfoView;
 class PhotoView;
+class MediaStringView;
 
 // Container view to display all Ambient Mode related views, i.e. photo frame,
 // weather info.
@@ -38,9 +39,12 @@ class ASH_EXPORT AmbientContainerView : public views::View {
   void Init();
 
   // Layouts its child views.
+  // TODO(meilinw): Use LayoutManagers to lay out children instead of overriding
+  // Layout(). See b/163170162.
   void LayoutPhotoView();
   void LayoutGlanceableInfoView();
   void LayoutAssistantView();
+  void LayoutMediaStringView();
 
   // Invoked on specific types of events.
   void HandleEvent();
@@ -51,6 +55,7 @@ class ASH_EXPORT AmbientContainerView : public views::View {
   PhotoView* photo_view_ = nullptr;
   AmbientAssistantContainerView* ambient_assistant_container_view_ = nullptr;
   GlanceableInfoView* glanceable_info_view_ = nullptr;
+  MediaStringView* media_string_view_ = nullptr;
 
   // Observes events from its host widget.
   std::unique_ptr<HostWidgetEventObserver> event_observer_;

ash/ambient/ui/media_string_view.cc

+// Copyright 2020 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 "ash/ambient/ui/media_string_view.h"
+
+#include <memory>
+#include <string>
+
+#include "ash/ambient/util/ambient_util.h"
+#include "ash/assistant/ui/assistant_view_ids.h"
+#include "ash/shell.h"
+#include "ash/shell_delegate.h"
+#include "base/strings/string16.h"
+#include "base/strings/utf_string_conversions.h"
+#include "services/media_session/public/mojom/media_session.mojom.h"
+#include "services/media_session/public/mojom/media_session_service.mojom.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/views/controls/label.h"
+#include "ui/views/layout/box_layout.h"
+
+namespace ash {
+
+namespace {
+
+// Typography.
+constexpr SkColor kTextColor = SK_ColorWHITE;
+constexpr char kMiddleDotSeparator[] = " \u00B7 ";
+constexpr char kPreceedingEighthNoteSymbol[] = "\u266A ";
+constexpr int kDefaultFontSizeDip = 64;
+constexpr int kMediaStringFontSizeDip = 16;
+
+}  // namespace
+
+MediaStringView::MediaStringView() {
+  SetID(AssistantViewID::kAmbientMediaStringView);
+  InitLayout();
+}
+
+MediaStringView::~MediaStringView() = default;
+
+const char* MediaStringView::GetClassName() const {
+  return "MediaStringView";
+}
+
+void MediaStringView::MediaSessionInfoChanged(
+    media_session::mojom::MediaSessionInfoPtr session_info) {
+  // Don't show the media string if session info is unavailable, or the active
+  // session is marked as sensitive.
+  if (!session_info || session_info->is_sensitive) {
+    SetVisible(false);
+    return;
+  }
+
+  bool is_paused = session_info->playback_state ==
+                   media_session::mojom::MediaPlaybackState::kPaused;
+
+  // Don't show the media string if paused.
+  SetVisible(!is_paused);
+}
+
+void MediaStringView::MediaSessionMetadataChanged(
+    const base::Optional<media_session::MediaMetadata>& metadata) {
+  media_session::MediaMetadata session_metadata =
+      metadata.value_or(media_session::MediaMetadata());
+
+  base::string16 media_string;
+  if (!session_metadata.title.empty() && !session_metadata.artist.empty()) {
+    media_string = session_metadata.title +
+                   base::UTF8ToUTF16(kMiddleDotSeparator) +
+                   session_metadata.artist;
+  } else if (!session_metadata.title.empty()) {
+    media_string = session_metadata.title;
+  } else {
+    media_string = session_metadata.artist;
+  }
+
+  // Formats the media string with a preceding music eighth note.
+  SetText(base::UTF8ToUTF16(kPreceedingEighthNoteSymbol) + media_string);
+}
+
+void MediaStringView::InitLayout() {
+  // This view will be drawn on its own layer instead of the layer of
+  // |PhotoView| which has a solid black background.
+  SetPaintToLayer();
+  layer()->SetFillsBoundsOpaquely(false);
+
+  // Defines the appearance.
+  SetAutoColorReadabilityEnabled(false);
+  SetEnabledColor(kTextColor);
+  SetFontList(ambient::util::GetDefaultFontlist().DeriveWithSizeDelta(
+      kMediaStringFontSizeDip - kDefaultFontSizeDip));
+
+  BindMediaControllerObserver();
+}
+
+void MediaStringView::BindMediaControllerObserver() {
+  media_session::mojom::MediaSessionService* service =
+      Shell::Get()->shell_delegate()->GetMediaSessionService();
+  // Service might be unavailable under some test environments.
+  if (!service)
+    return;
+
+  // Binds to the MediaControllerManager and create a MediaController for the
+  // current active media session so that we can observe it.
+  mojo::Remote<media_session::mojom::MediaControllerManager>
+      controller_manager_remote;
+  service->BindMediaControllerManager(
+      controller_manager_remote.BindNewPipeAndPassReceiver());
+  controller_manager_remote->CreateActiveMediaController(
+      media_controller_remote_.BindNewPipeAndPassReceiver());
+
+  // Observe the active media controller for changes.
+  media_controller_remote_->AddObserver(
+      observer_receiver_.BindNewPipeAndPassRemote());
+}
+
+}  // namespace ash

ash/ambient/ui/media_string_view.h

+// Copyright 2020 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 ASH_AMBIENT_UI_MEDIA_STRING_VIEW_H_
+#define ASH_AMBIENT_UI_MEDIA_STRING_VIEW_H_
+
+#include <string>
+#include "ash/app_menu/notification_item_view.h"
+#include "ash/public/cpp/ambient/ambient_ui_model.h"
+#include "mojo/public/cpp/bindings/receiver.h"
+#include "mojo/public/cpp/bindings/remote.h"
+#include "services/media_session/public/mojom/media_controller.mojom.h"
+#include "ui/views/controls/image_view.h"
+#include "ui/views/controls/label.h"
+
+namespace ash {
+
+// Container for displaying ongoing media information, including the name of the
+// media and the artist, formatted with a proceding music note symbol and a
+// middle dot separator.
+class MediaStringView : public views::Label,
+                        public media_session::mojom::MediaControllerObserver {
+ public:
+  MediaStringView();
+  MediaStringView(const MediaStringView&) = delete;
+  MediaStringView& operator=(const MediaStringView&) = delete;
+  ~MediaStringView() override;
+
+  // views::Label:
+  const char* GetClassName() const override;
+
+  // media_session::mojom::MediaControllerObserver:
+  void MediaSessionInfoChanged(
+      media_session::mojom::MediaSessionInfoPtr session_info) override;
+  void MediaSessionMetadataChanged(
+      const base::Optional<media_session::MediaMetadata>& metadata) override;
+  void MediaSessionActionsChanged(
+      const std::vector<media_session::mojom::MediaSessionAction>& actions)
+      override {}
+  void MediaSessionChanged(
+      const base::Optional<base::UnguessableToken>& request_id) override {}
+  void MediaSessionPositionChanged(
+      const base::Optional<media_session::MediaPosition>& position) override {}
+
+ private:
+  void InitLayout();
+
+  void BindMediaControllerObserver();
+
+  // Used to receive updates to the active media controller.
+  mojo::Remote<media_session::mojom::MediaController> media_controller_remote_;
+  mojo::Receiver<media_session::mojom::MediaControllerObserver>
+      observer_receiver_{this};
+};
+
+}  // namespace ash
+
+#endif  // ASH_AMBIENT_UI_MEDIA_STRING_VIEW_H_

ash/ambient/ui/media_string_view_unittest.cc

+// Copyright 2020 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 "ash/ambient/ui/media_string_view.h"
+
+#include "ash/ambient/test/ambient_ash_test_base.h"
+#include "base/strings/string16.h"
+#include "base/strings/utf_string_conversions.h"
+#include "services/media_session/public/mojom/media_session.mojom.h"
+
+namespace ash {
+
+using MediaStringViewTest = AmbientAshTestBase;
+
+TEST_F(MediaStringViewTest, ShowMediaTitleAndArtist) {
+  ShowAmbientScreen();
+
+  // Sets metadata for current session.
+  media_session::MediaMetadata metadata;
+  metadata.title = base::ASCIIToUTF16("title");
+  metadata.artist = base::ASCIIToUTF16("artist");
+
+  SimulateMediaMetadataChanged(metadata);
+
+  const base::string16 expected_text =
+      base::UTF8ToUTF16("\u266A title \u00B7 artist");
+  EXPECT_EQ(GetMediaStringView()->GetText(), expected_text);
+}
+
+TEST_F(MediaStringViewTest, ShowWhenMediaIsPlaying) {
+  ShowAmbientScreen();
+  EXPECT_FALSE(GetMediaStringView()->GetVisible());
+
+  // Sets media playstate for the current session.
+  SimulateMediaPlaybackStateChanged(
+      media_session::mojom::MediaPlaybackState::kPlaying);
+  EXPECT_TRUE(GetMediaStringView()->GetVisible());
+}
+
+TEST_F(MediaStringViewTest, DoNotShowWhenMediaIsPaused) {
+  ShowAmbientScreen();
+  EXPECT_FALSE(GetMediaStringView()->GetVisible());
+
+  // Sets media playstate for the current session.
+  SimulateMediaPlaybackStateChanged(
+      media_session::mojom::MediaPlaybackState::kPlaying);
+  EXPECT_TRUE(GetMediaStringView()->GetVisible());
+
+  // Simulates the ongoing media paused.
+  SimulateMediaPlaybackStateChanged(
+      media_session::mojom::MediaPlaybackState::kPaused);
+  EXPECT_FALSE(GetMediaStringView()->GetVisible());
+}
+
+}  // namespace ash

ash/assistant/ui/assistant_view_ids.h

@@ -43,6 +43,7 @@ enum AssistantViewID {
   kAmbientBackgroundImageView,
   kAmbientGlanceableInfoView,
   kAmbientAssistantDialogPlate,
+  kAmbientMediaStringView,
 };
 
 }  // namespace ash