Reland: Add UKM Document.OutliveTimeAfterShutdown

This is basically same as https://chromium-review.googlesource.com/c/chromium/src/+/647050.
This CL tries to reland the change after rebasing.

This CL adds a new UKM Document.OutliveTimeAfterShutdown, that is
recorded when a Document object survives 5, 10, 20 or 50 garbage
collections after detached. If a document outlives such long time, the
document might be leaked. The UKM would be very useful to know where such
leaky documents exist and to fix them.

Design doc: https://docs.google.com/document/d/1fbs5smdd-pBLLMpq7u8EkyddZILtI7CZPJlo_AA1kak/edit?usp=sharing

Bug: 757374
Change-Id: I1f64d2a9260d898c386bb948dd25a1c5586f8eb7
Reviewed-on: https://chromium-review.googlesource.com/722301
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510029}

third_party/WebKit/Source/core/dom/BUILD.gn

@@ -364,6 +364,7 @@ blink_core_sources("dom") {
 
   deps = [
     "//services/metrics/public/cpp:metrics_cpp",
+    "//services/metrics/public/cpp:ukm_builders",
     "//services/metrics/public/interfaces",
   ]
 }

third_party/WebKit/Source/core/dom/Document.cpp

@@ -261,6 +261,7 @@
 #include "public/platform/modules/insecure_input/insecure_input_service.mojom-blink.h"
 #include "public/platform/site_engagement.mojom-blink.h"
 #include "services/metrics/public/cpp/mojo_ukm_recorder.h"
+#include "services/metrics/public/cpp/ukm_builders.h"
 #include "services/metrics/public/interfaces/ukm_interface.mojom-shared.h"
 #include "services/service_manager/public/cpp/interface_provider.h"
 
@@ -311,6 +312,7 @@ class DocumentOutliveTimeReporter : public BlinkGCObserver {
     int outlive_time_count = GetOutliveTimeCount();
     if (outlive_time_count == 5 || outlive_time_count == 10) {
       const char* kUMAString = "Document.OutliveTimeAfterShutdown.GCCount";
+
       if (outlive_time_count == 5)
         UMA_HISTOGRAM_ENUMERATION(kUMAString, kGCCount5, kGCCountMax);
       else if (outlive_time_count == 10)
@@ -318,6 +320,11 @@ class DocumentOutliveTimeReporter : public BlinkGCObserver {
       else
         NOTREACHED();
     }
+
+    if (outlive_time_count == 5 || outlive_time_count == 10 ||
+        outlive_time_count == 20 || outlive_time_count == 50) {
+      document_->RecordUkmOutliveTimeAfterShutdown(outlive_time_count);
+    }
   }
 
  private:
@@ -3697,8 +3704,17 @@ void Document::SetURL(const KURL& url) {
   UpdateBaseURL();
   GetContextFeatures().UrlDidChange(this);
 
-  if (ukm_recorder_)
+  if (!ukm_recorder_ && IsInMainFrame()) {
+    ukm::mojom::UkmRecorderInterfacePtr interface;
+    frame_->GetInterfaceProvider().GetInterface(mojo::MakeRequest(&interface));
+    ukm_source_id_ = ukm::UkmRecorder::GetNewSourceID();
+    ukm_recorder_.reset(new ukm::MojoUkmRecorder(std::move(interface)));
+  }
+
+  if (ukm_recorder_) {
+    DCHECK(IsInMainFrame());
     ukm_recorder_->UpdateSourceURL(ukm_source_id_, url_);
+  }
 }
 
 KURL Document::ValidBaseElementURL() const {
@@ -7232,6 +7248,15 @@ void Document::RecordDeferredLoadReason(WouldLoadReason reason) {
   would_load_reason_ = reason;
 }
 
+void Document::RecordUkmOutliveTimeAfterShutdown(int outlive_time_count) {
+  if (!ukm_recorder_)
+    return;
+
+  ukm::builders::Document_OutliveTimeAfterShutdown(ukm_source_id_)
+      .SetGCCount(outlive_time_count)
+      .Record(ukm_recorder_.get());
+}
+
 DEFINE_TRACE_WRAPPERS(Document) {
   // node_lists_ are traced in their corresponding NodeListsNodeData, keeping
   // them only alive for live nodes. Otherwise we would keep lists of dead

third_party/WebKit/Source/core/dom/Document.h

@@ -1391,6 +1391,8 @@ class CORE_EXPORT Document : public ContainerNode,
   ukm::UkmRecorder* UkmRecorder();
   int64_t UkmSourceID() const;
 
+  void RecordUkmOutliveTimeAfterShutdown(int outlive_time_count);
+
  protected:
   Document(const DocumentInit&, DocumentClassFlags = kDefaultDocumentClass);
 

tools/metrics/ukm/ukm.xml

@@ -390,6 +390,24 @@ be describing additional metrics about the same event.
   </metric>
 </event>
 
+<event name="Document.OutliveTimeAfterShutdown">
+  <owner>hajimehoshi@chromium.org</owner>
+  <owner>keishi@chromium.org</owner>
+  <summary>
+    Recorded when a Document object survives certain number of garbage
+    collections after detached. It is expected that regular Document objects are
+    destroyed soon after detached, and if a document outlives longer, probably
+    this can be leaked.
+  </summary>
+  <metric name="GCCount">
+    <summary>
+      Measures the numbers of garbarge collection after the document is
+      detached. This is recorded when the number reached certain numbers like 5
+      or 10.
+    </summary>
+  </metric>
+</event>
+
 <event name="Event.ScrollUpdate.Touch">
   <owner>nzolghadr@chromium.org</owner>
   <summary>