DevTools: speed up getting of script URL in DOMSnapshotAgent

Use v8::StackTrace::CurrentStackTrace() rather than
v8_inspector::captureStackTrace() to capture stack trace when looking
for script origin. This allows us to bypass forced resolution of
location info (line numbers, method names etc) and when the related
v8 change is landed (http://crrev.com/c/v8/v8/+/2080663), greatly
speeds DOM operations on certain pages with DOMSnapshotAgent enabled.

Bug: 1057211
Change-Id: Ifbb5c7fb89b1f752f5d353d138d3b2c52bcd7e08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079165Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747775}

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

@@ -93,6 +93,53 @@ std::unique_ptr<protocol::DOMSnapshot::RareBooleanData> BooleanData() {
       .build();
 }
 
+String GetOriginUrlFast(int max_stack_depth) {
+  static const v8::StackTrace::StackTraceOptions stackTraceOptions =
+      static_cast<v8::StackTrace::StackTraceOptions>(v8::StackTrace::kDetailed);
+  v8::Isolate* isolate = v8::Isolate::GetCurrent();
+  DCHECK(isolate);
+
+  v8::Local<v8::StackTrace> v8StackTrace = v8::StackTrace::CurrentStackTrace(
+      isolate, max_stack_depth, stackTraceOptions);
+  if (v8StackTrace.IsEmpty())
+    return String();
+  for (int i = 0, frame_count = v8StackTrace->GetFrameCount(); i < frame_count;
+       ++i) {
+    v8::Local<v8::StackFrame> frame = v8StackTrace->GetFrame(isolate, i);
+    if (frame.IsEmpty())
+      continue;
+    v8::Local<v8::String> script_name = frame->GetScriptNameOrSourceURL();
+    if (script_name.IsEmpty() || !script_name->Length())
+      continue;
+    return ToCoreString(script_name);
+  }
+  return String();
+}
+
+String GetOriginUrl(const Node* node) {
+  v8::Isolate* isolate = v8::Isolate::GetCurrent();
+  ThreadDebugger* debugger = ThreadDebugger::From(isolate);
+  if (!isolate || !isolate->InContext() || !debugger)
+    return String();
+  v8::HandleScope handleScope(isolate);
+  // Try not getting the entire stack first.
+  String url = GetOriginUrlFast(/* maxStackSize=*/5);
+  if (!url.IsEmpty())
+    return url;
+  url = GetOriginUrlFast(/* maxStackSize=*/200);
+  if (!url.IsEmpty())
+    return url;
+  // If we did not get anything from the sync stack, let's try the slow
+  // way that also checks async stacks.
+  auto trace = debugger->GetV8Inspector()->captureStackTrace(true);
+  if (trace)
+    url = ToCoreString(trace->firstNonEmptySourceURL());
+  if (!url.IsEmpty())
+    return url;
+  // Fall back to document url.
+  return node->GetDocument().Url().GetString();
+}
+
 }  // namespace
 
 // Returns |layout_object|'s bounding box in document coordinates.
@@ -132,42 +179,15 @@ InspectorDOMSnapshotAgent::InspectorDOMSnapshotAgent(
 
 InspectorDOMSnapshotAgent::~InspectorDOMSnapshotAgent() = default;
 
-void InspectorDOMSnapshotAgent::GetOriginUrl(String* origin_url_ptr,
-                                             const Node* node) {
-  v8::Isolate* isolate = v8::Isolate::GetCurrent();
-  ThreadDebugger* debugger = ThreadDebugger::From(isolate);
-  if (!isolate || !isolate->InContext() || !debugger) {
-    origin_url_ptr = nullptr;
-    return;
-  }
-  // First try searching in one frame, since grabbing full trace is
-  // expensive.
-  auto trace = debugger->GetV8Inspector()->captureStackTrace(false);
-  if (!trace) {
-    origin_url_ptr = nullptr;
-    return;
-  }
-  if (!trace->firstNonEmptySourceURL().length())
-    trace = debugger->GetV8Inspector()->captureStackTrace(true);
-  String origin_url = ToCoreString(trace->firstNonEmptySourceURL());
-  if (origin_url.IsEmpty()) {
-    // Fall back to document url.
-    origin_url = node->GetDocument().Url().GetString();
-  }
-  *origin_url_ptr = origin_url;
-}
-
 void InspectorDOMSnapshotAgent::CharacterDataModified(
     CharacterData* character_data) {
-  String origin_url;
-  GetOriginUrl(&origin_url, character_data);
+  String origin_url = GetOriginUrl(character_data);
   if (origin_url)
     origin_url_map_->insert(DOMNodeIds::IdForNode(character_data), origin_url);
 }
 
 void InspectorDOMSnapshotAgent::DidInsertDOMNode(Node* node) {
-  String origin_url;
-  GetOriginUrl(&origin_url, node);
+  String origin_url = GetOriginUrl(node);
   if (origin_url)
     origin_url_map_->insert(DOMNodeIds::IdForNode(node), origin_url);
 }

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

@@ -95,8 +95,6 @@ class CORE_EXPORT InspectorDOMSnapshotAgent final
   int BuildLayoutTreeNode(LayoutObject*, Node*, int node_index);
   std::unique_ptr<protocol::Array<int>> BuildStylesForNode(Node*);
 
-  void GetOriginUrl(String*, const Node*);
-
   static void TraversePaintLayerTree(Document*, PaintOrderMap* paint_order_map);
   static void VisitPaintLayer(PaintLayer*, PaintOrderMap* paint_order_map);