DevTools: Introduce Landing page for Timeline panel.

third_party/WebKit/Source/devtools/BUILD.gn

Index: third_party/WebKit/Source/devtools/BUILD.gn
diff --git a/third_party/WebKit/Source/devtools/BUILD.gn b/third_party/WebKit/Source/devtools/BUILD.gn
index 5df790739d753b94c4c8437e0ff978ad4a2c9036..9131241e3012f66285c672248fb9180b8d39d016 100644
--- a/third_party/WebKit/Source/devtools/BUILD.gn
+++ b/third_party/WebKit/Source/devtools/BUILD.gn
@@ -738,6 +738,7 @@ devtools_layer_viewer_js_files = [
 devtools_timeline_js_files = [
   "front_end/timeline/invalidationsTree.css",
   "front_end/timeline/timelineFlamechartPopover.css",
+  "front_end/timeline/timelineLandingPage.css",
   "front_end/timeline/timelinePaintProfiler.css",
   "front_end/timeline/timelinePanel.css",
   "front_end/timeline/timelineStatusDialog.css",
@@ -748,6 +749,7 @@ devtools_timeline_js_files = [
   "front_end/timeline/TimelineFlameChart.js",
   "front_end/timeline/TimelineFlameChartView.js",
   "front_end/timeline/TimelineNetworkFlameChart.js",
+  "front_end/timeline/TimelineLandingPage.js",
   "front_end/timeline/TimelineLayersView.js",
   "front_end/timeline/TimelineLoader.js",
   "front_end/timeline/TimelinePaintProfilerView.js",