Adds UKM force deferred script counts for mainframe for DeferAllScript

Creates and populates new UKM PreviewsDeferAllScript event to report
the count of scripts force deferred in the mainframe.

Bug: 978568
Change-Id: I7e7d87d0a181559832e1a4c6a1682db543790434
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1715109Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Doug Arnett <dougarnett@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680567}

chrome/browser/previews/defer_all_script_browsertest.cc

@@ -199,7 +199,6 @@ class DeferAllScriptBrowserTest : public InProcessBrowserTest {
 IN_PROC_BROWSER_TEST_F(
     DeferAllScriptBrowserTest,
     DISABLE_ON_WIN_MAC_CHROMESOS(DeferAllScriptHttpsWhitelisted)) {
-  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
 
   GURL url = https_url();
 
@@ -207,6 +206,7 @@ IN_PROC_BROWSER_TEST_F(
   SetDeferAllScriptHintWithPageWithPattern(url, "*");
 
   base::HistogramTester histogram_tester;
+  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
 
   ui_test_utils::NavigateToURL(browser(), url);
 
@@ -228,12 +228,21 @@ IN_PROC_BROWSER_TEST_F(
       "Blink.Script.ForceDeferredScripts.Mainframe", 2, 1);
   histogram_tester.ExpectUniqueSample(
       "Blink.Script.ForceDeferredScripts.Mainframe.External", 1, 1);
+
+  // Verify UKM force deferred count entries.
+  using UkmDeferEntry = ukm::builders::PreviewsDeferAllScript;
+  auto entries = test_ukm_recorder.GetEntriesByName(UkmDeferEntry::kEntryName);
+  ASSERT_EQ(1u, entries.size());
+  auto* entry = entries.at(0);
+  test_ukm_recorder.ExpectEntryMetric(
+      entry, UkmDeferEntry::kforce_deferred_scripts_mainframeName, 2);
+  test_ukm_recorder.ExpectEntryMetric(
+      entry, UkmDeferEntry::kforce_deferred_scripts_mainframe_externalName, 1);
 }
 
 IN_PROC_BROWSER_TEST_F(
     DeferAllScriptBrowserTest,
     DISABLE_ON_WIN_MAC_CHROMESOS(DeferAllScriptHttpsNotWhitelisted)) {
-  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
 
   GURL url = https_url();
 
@@ -241,6 +250,7 @@ IN_PROC_BROWSER_TEST_F(
   SetDeferAllScriptHintWithPageWithPattern(url, "/NoMatch/");
 
   base::HistogramTester histogram_tester;
+  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
 
   // The URL is not whitelisted.
   ui_test_utils::NavigateToURL(browser(), url);
@@ -274,14 +284,13 @@ IN_PROC_BROWSER_TEST_F(
         {{"force_coin_flip_always_holdback", "true"}}}},
       {previews::features::kOfflinePreviews});
 
-  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
-
   GURL url = https_url();
 
   // Whitelist DeferAllScript for any path for the url's host.
   SetDeferAllScriptHintWithPageWithPattern(url, "*");
 
   base::HistogramTester histogram_tester;
+  ukm::TestAutoSetUkmRecorder test_ukm_recorder;
 
   ui_test_utils::NavigateToURL(browser(), url);
 

third_party/blink/renderer/core/script/html_parser_script_runner.cc

@@ -27,6 +27,7 @@
 
 #include <inttypes.h>
 #include <memory>
+#include "services/metrics/public/cpp/ukm_builders.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/platform/task_type.h"
 #include "third_party/blink/renderer/core/dom/document_parser_timing.h"
@@ -649,9 +650,13 @@ void HTMLParserScriptRunner::ProcessScriptElementInternal(
 }
 
 void HTMLParserScriptRunner::RecordMetricsAtParseEnd() const {
-  // This method is called just before starting execution of force deferred
+  // This method is called just before starting execution of force defer
   // scripts in order to capture the all force deferred scripts in
   // |force_deferred_scripts_| before any are popped for execution.
+
+  if (!document_->GetFrame())
+    return;
+
   if (!force_deferred_scripts_.IsEmpty()) {
     uint32_t force_deferred_external_script_count = 0;
     for (const auto& pending_script : force_deferred_scripts_) {
@@ -664,6 +669,13 @@ void HTMLParserScriptRunner::RecordMetricsAtParseEnd() const {
       UMA_HISTOGRAM_COUNTS_100(
           "Blink.Script.ForceDeferredScripts.Mainframe.External",
           force_deferred_external_script_count);
+      if (document_->UkmRecorder()) {
+        ukm::builders::PreviewsDeferAllScript(document_->UkmSourceID())
+            .Setforce_deferred_scripts_mainframe(force_deferred_scripts_.size())
+            .Setforce_deferred_scripts_mainframe_external(
+                force_deferred_external_script_count)
+            .Record(document_->UkmRecorder());
+      }
     } else {
       UMA_HISTOGRAM_COUNTS_100("Blink.Script.ForceDeferredScripts.Subframe",
                                force_deferred_scripts_.size());

tools/metrics/ukm/ukm.xml

@@ -6147,6 +6147,28 @@ be describing additional metrics about the same event.
   </metric>
 </event>
 
+<event name="PreviewsDeferAllScript" singular="True">
+  <owner>dougarnett@chromium.org</owner>
+  <summary>
+    Metrics associated with the intervention of deferring the execution of
+    synchronous script (typically due to a DeferAllScript Preview). This is
+    recorded when the HTML parsing of a mainframe has completed.
+  </summary>
+  <metric name="force_deferred_scripts_mainframe">
+    <summary>
+      The total number of mainframe scripts (inline and external) whose
+      execution was force deferred (i.e., that otherwise would have been render
+      blocking).
+    </summary>
+  </metric>
+  <metric name="force_deferred_scripts_mainframe_external">
+    <summary>
+      The total number of mainframe external scripts whose execution was force
+      deferred (i.e., that otherwise would have been render blocking).
+    </summary>
+  </metric>
+</event>
+
 <event name="PreviewsResourceLoadingHints" singular="True">
   <owner>jegray@chromium.org</owner>
   <summary>