Added CaptureSnapshotDuration metric to Performance.getMetrics.

This metric tracks time spent in DOMSnapshot::captureSnapshot calls.

Drive by: subtracted v8 compilation duration from tasks duration
when calculating other tasks duration. This ensures correct stacking
known activities.

Change-Id: I79c6926d516c02717b68ea426e3e99a7d9fd665e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2062691
Commit-Queue: Peter Kvitek <kvitekp@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742888}

third_party/blink/renderer/core/exported/web_dev_tools_agent_impl.cc

@@ -252,17 +252,18 @@ void WebDevToolsAgentImpl::AttachSession(DevToolsSession* session,
                                                       session->V8Session());
   session->Append(dom_debugger_agent);
 
+  InspectorPerformanceAgent* performance_agent =
+      MakeGarbageCollected<InspectorPerformanceAgent>(inspected_frames);
+  session->Append(performance_agent);
+
   session->Append(MakeGarbageCollected<InspectorDOMSnapshotAgent>(
-      inspected_frames, dom_debugger_agent));
+      inspected_frames, dom_debugger_agent, performance_agent));
 
   session->Append(MakeGarbageCollected<InspectorAnimationAgent>(
       inspected_frames, css_agent, session->V8Session()));
 
   session->Append(MakeGarbageCollected<InspectorMemoryAgent>(inspected_frames));
 
-  session->Append(
-      MakeGarbageCollected<InspectorPerformanceAgent>(inspected_frames));
-
   session->Append(
       MakeGarbageCollected<InspectorApplicationCacheAgent>(inspected_frames));
 

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

@@ -125,9 +125,11 @@ PhysicalRect InspectorDOMSnapshotAgent::TextFragmentRectInDocument(
 
 InspectorDOMSnapshotAgent::InspectorDOMSnapshotAgent(
     InspectedFrames* inspected_frames,
-    InspectorDOMDebuggerAgent* dom_debugger_agent)
+    InspectorDOMDebuggerAgent* dom_debugger_agent,
+    InspectorPerformanceAgent* performance_agent)
     : inspected_frames_(inspected_frames),
       dom_debugger_agent_(dom_debugger_agent),
+      performance_agent_(performance_agent),
       enabled_(&agent_state_, /*default_value=*/false) {}
 
 InspectorDOMSnapshotAgent::~InspectorDOMSnapshotAgent() = default;
@@ -226,6 +228,17 @@ protocol::Response InspectorDOMSnapshotAgent::captureSnapshot(
     std::unique_ptr<protocol::Array<protocol::DOMSnapshot::DocumentSnapshot>>*
         documents,
     std::unique_ptr<protocol::Array<String>>* strings) {
+  struct ScopedPerformanceReporter {
+    explicit ScopedPerformanceReporter(
+        InspectorPerformanceAgent* performance_agent)
+        : performance_agent(performance_agent) {
+      performance_agent->WillCaptureSnapshot();
+    }
+    ~ScopedPerformanceReporter() { performance_agent->DidCaptureSnapshot(); }
+    InspectorPerformanceAgent* performance_agent;
+    STACK_ALLOCATED();
+  } scoped_performance_reporter(performance_agent_);
+
   // This function may kick the layout, but external clients may call this
   // function outside of the layout phase.
   FontCachePurgePreventer fontCachePurgePreventer;
@@ -721,6 +734,7 @@ void InspectorDOMSnapshotAgent::VisitPaintLayer(
 void InspectorDOMSnapshotAgent::Trace(Visitor* visitor) {
   visitor->Trace(inspected_frames_);
   visitor->Trace(dom_debugger_agent_);
+  visitor->Trace(performance_agent_);
   visitor->Trace(document_order_map_);
   InspectorBaseAgent::Trace(visitor);
 }

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

@@ -9,6 +9,7 @@
 #include "third_party/blink/renderer/core/css/css_property_names.h"
 #include "third_party/blink/renderer/core/dom/dom_node_ids.h"
 #include "third_party/blink/renderer/core/inspector/inspector_base_agent.h"
+#include "third_party/blink/renderer/core/inspector/inspector_performance_agent.h"
 #include "third_party/blink/renderer/core/inspector/protocol/DOMSnapshot.h"
 #include "third_party/blink/renderer/core/layout/layout_text.h"
 #include "third_party/blink/renderer/platform/wtf/hash_map.h"
@@ -26,7 +27,9 @@ class PaintLayer;
 class CORE_EXPORT InspectorDOMSnapshotAgent final
     : public InspectorBaseAgent<protocol::DOMSnapshot::Metainfo> {
  public:
-  InspectorDOMSnapshotAgent(InspectedFrames*, InspectorDOMDebuggerAgent*);
+  InspectorDOMSnapshotAgent(InspectedFrames*,
+                            InspectorDOMDebuggerAgent*,
+                            InspectorPerformanceAgent*);
   ~InspectorDOMSnapshotAgent() override;
   void Trace(Visitor*) override;
 
@@ -128,6 +131,7 @@ class CORE_EXPORT InspectorDOMSnapshotAgent final
   DocumentOrderMap document_order_map_;
   Member<InspectedFrames> inspected_frames_;
   Member<InspectorDOMDebuggerAgent> dom_debugger_agent_;
+  Member<InspectorPerformanceAgent> performance_agent_;
   InspectorAgentState::Boolean enabled_;
   DISALLOW_COPY_AND_ASSIGN(InspectorDOMSnapshotAgent);
 };

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

@@ -57,6 +57,7 @@ void InspectorPerformanceAgent::InnerEnable() {
   task_start_ticks_ = base::TimeTicks();
   script_start_ticks_ = base::TimeTicks();
   v8compile_start_ticks_ = base::TimeTicks();
+  capture_snapshot_start_ticks_ = base::TimeTicks();
   thread_time_origin_ = GetThreadTimeNow();
 }
 
@@ -153,6 +154,8 @@ Response InspectorPerformanceAgent::getMetrics(
   AppendMetric(result.get(), "LayoutDuration", layout_duration_.InSecondsF());
   AppendMetric(result.get(), "RecalcStyleDuration",
                recalc_style_duration_.InSecondsF());
+  AppendMetric(result.get(), "CaptureSnapshotDuration",
+               capture_snapshot_duration_.InSecondsF());
 
   base::TimeDelta script_duration = script_duration_;
   if (!script_start_ticks_.is_null())
@@ -173,7 +176,8 @@ Response InspectorPerformanceAgent::getMetrics(
   // Compute task time not accounted for by other metrics.
   base::TimeDelta other_tasks_duration =
       task_duration -
-      (script_duration + recalc_style_duration_ + layout_duration_);
+      (script_duration + v8compile_duration + recalc_style_duration_ +
+       layout_duration_ + capture_snapshot_duration_);
   AppendMetric(result.get(), "TaskOtherDuration",
                other_tasks_duration.InSecondsF());
 
@@ -309,6 +313,18 @@ void InspectorPerformanceAgent::DidProcessTask(base::TimeTicks start_time,
   task_start_ticks_ = base::TimeTicks();
 }
 
+void InspectorPerformanceAgent::WillCaptureSnapshot() {
+  capture_snapshot_start_ticks_ = GetTimeTicksNow();
+}
+
+void InspectorPerformanceAgent::DidCaptureSnapshot() {
+  if (!capture_snapshot_start_ticks_.is_null()) {
+    capture_snapshot_duration_ +=
+        GetTimeTicksNow() - capture_snapshot_start_ticks_;
+  }
+  capture_snapshot_start_ticks_ = base::TimeTicks();
+}
+
 void InspectorPerformanceAgent::Trace(Visitor* visitor) {
   visitor->Trace(inspected_frames_);
   InspectorBaseAgent<protocol::Performance::Metainfo>::Trace(visitor);

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

@@ -62,6 +62,10 @@ class CORE_EXPORT InspectorPerformanceAgent final
   void DidProcessTask(base::TimeTicks start_time,
                       base::TimeTicks end_time) override;
 
+  // Called from DOMSnapshotAgent
+  void WillCaptureSnapshot();
+  void DidCaptureSnapshot();
+
  private:
   void ScriptStarts();
   void ScriptEnds();
@@ -80,6 +84,8 @@ class CORE_EXPORT InspectorPerformanceAgent final
   base::TimeTicks task_start_ticks_;
   base::TimeDelta v8compile_duration_;
   base::TimeTicks v8compile_start_ticks_;
+  base::TimeDelta capture_snapshot_duration_;
+  base::TimeTicks capture_snapshot_start_ticks_;
   base::TimeTicks thread_time_origin_;
   uint64_t layout_count_ = 0;
   uint64_t recalc_style_count_ = 0;

third_party/blink/web_tests/http/tests/devtools/oopif/oopif-performance-monitor-expected.txt

@@ -4,6 +4,7 @@ Tests stability of performance metrics list.
 Metrics reported:
 AdSubframes
 AudioHandlers
+CaptureSnapshotDuration
 ContextLifecycleStateObservers
 DetachedScriptStates
 Documents

third_party/blink/web_tests/inspector-protocol/performance/perf-push-metrics-expected.txt

@@ -22,6 +22,7 @@ title: test1
 	RecalcStyleCount
 	LayoutDuration
 	RecalcStyleDuration
+	CaptureSnapshotDuration
 	ScriptDuration
 	V8CompileDuration
 	TaskDuration
@@ -55,6 +56,7 @@ title: test1
 	RecalcStyleCount
 	LayoutDuration
 	RecalcStyleDuration
+	CaptureSnapshotDuration
 	ScriptDuration
 	V8CompileDuration
 	TaskDuration
@@ -88,6 +90,7 @@ title:
 	RecalcStyleCount
 	LayoutDuration
 	RecalcStyleDuration
+	CaptureSnapshotDuration
 	ScriptDuration
 	V8CompileDuration
 	TaskDuration