DevTools: Introduce Landing page for Timeline panel.

third_party/WebKit/Source/devtools/front_end/timeline/timelineLandingPage.css

+/*
+ * Copyright (c) 2016 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.
+ */
+
+.timeline-landing-page {
+    display: flex;
+    align-items: stretch;
+    width: 500px;
+    align-self: center;
+    padding: 10px;
+}
+
+.timeline-landing-page .timeline-perspective-header-bar {
+    display: flex;
+}
+
+.timeline-landing-page .timeline-perspective-header input[type=radio] {
+    display: none;
+}
+
+.timeline-landing-page .timeline-perspective-header label {
+    display: inline-block;
+    cursor: pointer;
+    position: relative;
+    padding: 6px 16px;
+    font-size: 15px;
+    border-bottom: 2px solid #eee;
+}
+
+.timeline-landing-page .timeline-perspective-header label:hover {
+    background-color: rgba(0, 0, 0, 0.05);
+}
+
+.timeline-landing-page .timeline-perspective-header input:checked + label {
+    border-bottom-color: #3E82F7;
+}
+
+.timeline-landing-page .timeline-perspective-body {
+    display: flex;
+    flex-direction: column;
+    align-items: flex-start;
+    line-height: 1.5;
+    margin: 12px 16px;
+    white-space: pre-line;
+}
+
+.timeline-landing-page .timeline-perspective-body > div {
+    margin-bottom: 12px;
+}
+
+.timeline-landing-page .timeline-perspective-footer button {
+    width: 80px;
+    height: 26px;
+    margin: 0 16px;
+}
+
+.timeline-landing-page .recording-setting {
+    display: flex;
+    flex-direction: row;
+    align-items: flex-start;
+    margin-bottom: 2px !important;
+}
+
+.timeline-landing-page .recording-setting input {
+    margin-left: 0;
+    margin-right: 8px;
+}
+
+.timeline-landing-page .recording-setting label {
+    width: 100px;
+}
+
+.timeline-landing-page .recording-setting-description {
+    color: #999;
+    width: 350px;
+}