DevTools overlay: add support for showing web vitals HUD

Add an ability to enable HUD display for performance metric on a per-renderer
basis through CDP.

Bug: 1152089
Change-Id: Ia6f097fc90ceae5a3e9dc878d7880adbf02ce7be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2639393Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845278}

third_party/blink/public/devtools_protocol/browser_protocol.pdl

@@ -6041,6 +6041,11 @@ experimental domain Overlay
       # True for showing hit-test borders
       boolean show
 
+  # Request that backend shows an overlay with web vital metrics.
+  command setShowWebVitals
+    parameters
+      boolean show
+
   # Paints viewport size upon main frame resize.
   command setShowViewportSizeOnResize
     parameters

third_party/blink/renderer/core/inspector/inspector_overlay_agent.cc

@@ -370,6 +370,7 @@ InspectorOverlayAgent::InspectorOverlayAgent(
       show_layout_shift_regions_(&agent_state_, false),
       show_scroll_bottleneck_rects_(&agent_state_, false),
       show_hit_test_borders_(&agent_state_, false),
+      show_web_vitals_(&agent_state_, false),
       show_size_on_resize_(&agent_state_, false),
       paused_in_debugger_message_(&agent_state_, String()),
       inspect_mode_(&agent_state_, protocol::Overlay::InspectModeEnum::None),
@@ -601,6 +602,25 @@ Response InspectorOverlayAgent::setShowViewportSizeOnResize(bool show) {
   return Response::Success();
 }
 
+Response InspectorOverlayAgent::setShowWebVitals(bool show) {
+  show_web_vitals_.Set(show);
+  if (show) {
+    Response response = CompositingEnabled();
+    if (!response.IsSuccess())
+      return response;
+  }
+  auto* widget_impl =
+      static_cast<WebFrameWidgetImpl*>(frame_impl_->LocalRoot()->FrameWidget());
+  // While a frame is being detached the inspector will shutdown and
+  // turn off debug overlays, but the WebFrameWidget is already gone.
+  if (widget_impl) {
+    cc::LayerTreeDebugState debug_state = widget_impl->GetLayerTreeDebugState();
+    debug_state.show_web_vital_metrics = show;
+    widget_impl->SetLayerTreeDebugState(debug_state);
+  }
+  return Response::Success();
+}
+
 Response InspectorOverlayAgent::setPausedInDebuggerMessage(
     Maybe<String> message) {
   paused_in_debugger_message_.Set(message.fromMaybe(String()));

third_party/blink/renderer/core/inspector/inspector_overlay_agent.h

@@ -169,6 +169,7 @@ class CORE_EXPORT InspectorOverlayAgent final
   protocol::Response setShowFPSCounter(bool) override;
   protocol::Response setShowScrollBottleneckRects(bool) override;
   protocol::Response setShowHitTestBorders(bool) override;
+  protocol::Response setShowWebVitals(bool) override;
   protocol::Response setShowViewportSizeOnResize(bool) override;
   protocol::Response setPausedInDebuggerMessage(
       protocol::Maybe<String>) override;
@@ -315,6 +316,7 @@ class CORE_EXPORT InspectorOverlayAgent final
   InspectorAgentState::Boolean show_layout_shift_regions_;
   InspectorAgentState::Boolean show_scroll_bottleneck_rects_;
   InspectorAgentState::Boolean show_hit_test_borders_;
+  InspectorAgentState::Boolean show_web_vitals_;
   InspectorAgentState::Boolean show_size_on_resize_;
   InspectorAgentState::String paused_in_debugger_message_;
   InspectorAgentState::String inspect_mode_;