DevTools: [timeline] Include other thread costs in overview

Source/devtools/front_end/timeline/timelinePanel.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * 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.
@@ skipping 250 matching lines @@
     font-weight: bold;
     text-transform: uppercase;
     z-index: -100;
     margin-left: 10px;
 }
 
 #timeline-overview-network {
     flex-basis: 25px;
 }
 
-#timeline-overview-main-thread,
+#timeline-overview-cpu-activity,
 #timeline-overview-framerate,
 #timeline-overview-memory {
     flex-basis: 21px;
 }
 
 #timeline-overview-filmstrip {
     flex-basis: 81px;
 }
 
 .overview-strip::before {
     content: "";
     position: absolute;
     right: 0;
     top: 0;
     bottom: 0;
     left: 0;
     color: #888;
     text-align: right;
     padding: 1px 4px;
     font-size: 9px;
     border-bottom: 1px solid hsla(0, 0%, 0%, 0.06);
     z-index: -200;
 }
 
 #timeline-overview-responsiveness::before {
     display: none;
 }
 
-#timeline-overview-main-thread::before {
+#timeline-overview-cpu-activity::before {
     content: "100%";
 }
 
+#timeline-overview-cpu-activity .background {
+    opacity: 0.15;
+    z-index: -10;
+}
+
 #timeline-overview-framerate::before {
     content: "60 fps";
 }
 
 #timeline-overview-responsiveness {
     flex-basis: 6px;
     margin-top: 1px !important;
 }
 
 #timeline-overview-input {
@@ skipping 739 matching lines @@
     position: absolute;
     right: -2px;
     bottom: 0px;
     border-bottom: 1px solid hsl(0, 100%, 74%);
 }
 
 .timeline-tree-view .data-grid .selected .background-bar {
     background-color: rgba(255,255,255,0.25);
     border-bottom-color: transparent;
 }