Reland MD Audio Player.

ui/file_manager/audio_player/elements/track_list.css

Index: ui/file_manager/audio_player/elements/track_list.css
diff --git a/ui/file_manager/audio_player/elements/track_list.css b/ui/file_manager/audio_player/elements/track_list.css
index 1b3f3d55c4e4d3d1f2250b3d04a38a2c2ff2c455..a2f31a29a061606a3c91f251ac529e6c3d22ec6a 100644
--- a/ui/file_manager/audio_player/elements/track_list.css
+++ b/ui/file_manager/audio_player/elements/track_list.css
@@ -4,9 +4,9 @@
 
 :host {
   align-items: center;
-  background: #f5f5f5;
+  background: rgb(245, 245, 245);
   bottom: 72px;  /* Room for the controls bar. */
-  color: #3d3d3d;
+  color: rgb(51, 51, 51);
   cursor: default;
   display: flex;
   flex-direction: column;
@@ -26,9 +26,8 @@
   display: flex;
   flex: 0 0 auto;
   flex-direction: row;
-  height: 44px;
+  height: 48px;
   justify-content: flex-start;
-  padding-left: 20px;
   width: 100%;
 }
 
@@ -36,9 +35,32 @@
   display: none;
 }
 
-/* In the expanded mode the selected track is highlighted. */
-.track[active] {
-  background-color: rgb(66, 129, 244);
+:host([expanded]) > .track:hover {
+  background-color: rgba(0, 0, 0, 0.08);
+}
+
+/* Track icon. */
+.track .icon {
+  background-position: center;
+  background-repeat: no-repeat;
+  flex: none;
+  height: 32px;
+  margin: 8px;
+  pointer-events: none;
+  width: 32px;
+}
+
+.track:hover .icon {
+  background-image: -webkit-image-set(
+      url(../assets/100/playlist_play.png) 1x,
+      url(../assets/200/playlist_play.png) 2x);
+  pointer-events: auto;
+}
+
+.track[active] .icon {
+  background-image: -webkit-image-set(
+      url(../assets/100/playlist_now_playing.png) 1x,
+      url(../assets/200/playlist_now_playing.png) 2x);
 }
 
 /* Track data. */
@@ -54,22 +76,18 @@
 
 .track .data .data-title,
 .track .data .data-artist {
-  font-size: 12px;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
 .track .data .data-title {
-  color: #343434;
-  font-weight: bold;
+  color: rgb(51, 51, 51);
+  font-size: 13px;
+  font-weight: 500;
 }
 
 .track .data .data-artist {
-  color: #969696;
-}
-
-.track[active] .data .data-title,
-.track[active] .data .data-artist {
-  color: #fff;
+  color: rgb(100, 100, 100);
+  font-size: 12px;
 }