Remove custom pausing logic from HTMLDocumentParser

All it does is cancel a timer and restart it when unpausing, which
is unnecessary as the underlying task queue will be paused, too.

HTMLDocumentParser had recently been made a
ContextLifecycleStateObserver, which had caused a substantial
slowdown in perf_tests/parser/tiny-innerHTML.html. This CL removes
that inheritance and reverses the slowdown.

Bug: 1030905
Change-Id: I4c296869b60db8c152c14cf1619051c21918ef82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1955849
Commit-Queue: Nate Chapin <japhet@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Auto-Submit: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#723497}

third_party/blink/renderer/core/html/parser/html_document_parser.cc

@@ -131,7 +131,6 @@ HTMLDocumentParser::HTMLDocumentParser(Document& document,
                                        ParserContentPolicy content_policy,
                                        ParserSynchronizationPolicy sync_policy)
     : ScriptableDocumentParser(document, content_policy),
-      ContextLifecycleStateObserver(&document),
       options_(&document),
       reentry_permit_(HTMLParserReentryPermit::Create()),
       token_(sync_policy == kForceSynchronousParsing
@@ -160,8 +159,6 @@ HTMLDocumentParser::HTMLDocumentParser(Document& document,
   // Threading is not allowed in prefetch mode.
   DCHECK(!document.IsPrefetchOnly() || !ShouldUseThreading());
 
-  UpdateStateIfNeeded();
-
   // Don't create preloader for parsing clipboard content.
   if (content_policy == kDisallowScriptingAndPluginContent)
     return;
@@ -194,7 +191,6 @@ void HTMLDocumentParser::Trace(Visitor* visitor) {
   visitor->Trace(script_runner_);
   visitor->Trace(preloader_);
   ScriptableDocumentParser::Trace(visitor);
-  ContextLifecycleStateObserver::Trace(visitor);
   HTMLParserScriptRunnerHost::Trace(visitor);
 }
 
@@ -390,12 +386,8 @@ void HTMLDocumentParser::EnqueueTokenizedChunk(
 
   speculations_.push_back(std::move(chunk));
 
-  if (!IsPaused() && !IsScheduledForUnpause()) {
-    if (GetDocument()->IsContextPaused())
-      parser_scheduler_->ForceUnpauseAfterYield();
-    else
-      parser_scheduler_->ScheduleForUnpause();
-  }
+  if (!IsPaused() && !IsScheduledForUnpause())
+    parser_scheduler_->ScheduleForUnpause();
 }
 
 void HTMLDocumentParser::DidReceiveEncodingDataFromBackgroundParser(
@@ -1119,16 +1111,6 @@ void HTMLDocumentParser::ParseDocumentFragment(
   parser->Detach();
 }
 
-void HTMLDocumentParser::ContextLifecycleStateChanged(
-    mojom::FrameLifecycleState state) {
-  if (!parser_scheduler_)
-    return;
-  if (state == mojom::FrameLifecycleState::kRunning)
-    parser_scheduler_->Unpause();
-  else
-    parser_scheduler_->Pause();
-}
-
 void HTMLDocumentParser::AppendBytes(const char* data, size_t length) {
   if (!length || IsStopped())
     return;

third_party/blink/renderer/core/html/parser/html_document_parser.h

@@ -32,7 +32,6 @@
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/dom/parser_content_policy.h"
 #include "third_party/blink/renderer/core/dom/scriptable_document_parser.h"
-#include "third_party/blink/renderer/core/execution_context/context_lifecycle_state_observer.h"
 #include "third_party/blink/renderer/core/html/parser/background_html_input_stream.h"
 #include "third_party/blink/renderer/core/html/parser/html_input_stream.h"
 #include "third_party/blink/renderer/core/html/parser/html_parser_options.h"
@@ -66,7 +65,6 @@ class HTMLResourcePreloader;
 class HTMLTreeBuilder;
 
 class CORE_EXPORT HTMLDocumentParser : public ScriptableDocumentParser,
-                                       public ContextLifecycleStateObserver,
                                        private HTMLParserScriptRunnerHost {
   USING_GARBAGE_COLLECTED_MIXIN(HTMLDocumentParser);
   USING_PRE_FINALIZER(HTMLDocumentParser, Dispose);
@@ -102,8 +100,6 @@ class CORE_EXPORT HTMLDocumentParser : public ScriptableDocumentParser,
   bool IsParsingAtLineNumber() const final;
   OrdinalNumber LineNumber() const final;
 
-  void ContextLifecycleStateChanged(mojom::FrameLifecycleState) final;
-
   HTMLParserReentryPermit* ReentryPermit() { return reentry_permit_.get(); }
 
   struct TokenizedChunk {

third_party/blink/renderer/core/html/parser/html_parser_scheduler.cc

@@ -51,9 +51,7 @@ void SpeculationsPumpSession::AddedElementTokens(size_t count) {
 HTMLParserScheduler::HTMLParserScheduler(
     HTMLDocumentParser* parser,
     scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner)
-    : parser_(parser),
-      loading_task_runner_(std::move(loading_task_runner)),
-      is_paused_with_active_timer_(false) {}
+    : parser_(parser), loading_task_runner_(std::move(loading_task_runner)) {}
 
 HTMLParserScheduler::~HTMLParserScheduler() = default;
 
@@ -62,37 +60,18 @@ void HTMLParserScheduler::Trace(Visitor* visitor) {
 }
 
 bool HTMLParserScheduler::IsScheduledForUnpause() const {
-  return is_paused_with_active_timer_ ||
-         cancellable_continue_parse_task_handle_.IsActive();
+  return cancellable_continue_parse_task_handle_.IsActive();
 }
 
 void HTMLParserScheduler::ScheduleForUnpause() {
-  DCHECK(!is_paused_with_active_timer_);
   cancellable_continue_parse_task_handle_ =
       PostCancellableTask(*loading_task_runner_, FROM_HERE,
                           WTF::Bind(&HTMLParserScheduler::ContinueParsing,
                                     WrapWeakPersistent(this)));
 }
 
-void HTMLParserScheduler::Pause() {
-  DCHECK(!is_paused_with_active_timer_);
-  if (!cancellable_continue_parse_task_handle_.IsActive())
-    return;
-  is_paused_with_active_timer_ = true;
-  cancellable_continue_parse_task_handle_.Cancel();
-}
-
-void HTMLParserScheduler::Unpause() {
-  DCHECK(!cancellable_continue_parse_task_handle_.IsActive());
-  if (!is_paused_with_active_timer_)
-    return;
-  is_paused_with_active_timer_ = false;
-  ScheduleForUnpause();
-}
-
 void HTMLParserScheduler::Detach() {
   cancellable_continue_parse_task_handle_.Cancel();
-  is_paused_with_active_timer_ = false;
 }
 
 inline bool HTMLParserScheduler::ShouldYield(
@@ -131,11 +110,6 @@ bool HTMLParserScheduler::YieldIfNeeded(const SpeculationsPumpSession& session,
   return false;
 }
 
-void HTMLParserScheduler::ForceUnpauseAfterYield() {
-  DCHECK(!cancellable_continue_parse_task_handle_.IsActive());
-  is_paused_with_active_timer_ = true;
-}
-
 void HTMLParserScheduler::ContinueParsing() {
   parser_->ResumeParsingAfterYield();
 }

third_party/blink/renderer/core/html/parser/html_parser_scheduler.h

@@ -64,18 +64,6 @@ class HTMLParserScheduler final : public GarbageCollected<HTMLParserScheduler> {
   void ScheduleForUnpause();
   bool YieldIfNeeded(const SpeculationsPumpSession&, bool starting_script);
 
-  /**
-   * Can only be called if this scheduler is paused. If this is called,
-   * then after the scheduler is resumed by calling resume(), this call
-   * ensures that HTMLDocumentParser::resumeAfterYield will be called. Used to
-   * signal this scheduler that the background html parser sent chunks to
-   * HTMLDocumentParser while it was paused.
-   */
-  void ForceUnpauseAfterYield();
-
-  void Pause();
-  void Unpause();
-
   void Detach();  // Clear active tasks if any.
 
   void Trace(Visitor*);
@@ -88,7 +76,6 @@ class HTMLParserScheduler final : public GarbageCollected<HTMLParserScheduler> {
   scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner_;
 
   TaskHandle cancellable_continue_parse_task_handle_;
-  bool is_paused_with_active_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(HTMLParserScheduler);
 };

third_party/blink/web_tests/http/tests/activedomobject/media-expected.txt

 Tests that reparenting media elements also reparents ActiveDOMObject.
 
 Before Reparenting
-PASS: internals.contextLifecycleStateObserverObjectCount(document) should be '1' and is.
-PASS: internals.contextLifecycleStateObserverObjectCount(iframe) should be '4' and is.
+PASS: internals.contextLifecycleStateObserverObjectCount(document) should be '0' and is.
+PASS: internals.contextLifecycleStateObserverObjectCount(iframe) should be '3' and is.
 After Reparenting
-PASS: internals.contextLifecycleStateObserverObjectCount(document) should be '4' and is.
-PASS: internals.contextLifecycleStateObserverObjectCount(iframe) should be '2' and is.
+PASS: internals.contextLifecycleStateObserverObjectCount(document) should be '3' and is.
+PASS: internals.contextLifecycleStateObserverObjectCount(iframe) should be '1' and is.

third_party/blink/web_tests/http/tests/activedomobject/media.html

@@ -10,8 +10,8 @@
         window.iframe = document.querySelector('iframe').contentDocument;
 
         log('Before Reparenting');
-        shouldBe('internals.contextLifecycleStateObserverObjectCount(document)', 1);
-        shouldBe('internals.contextLifecycleStateObserverObjectCount(iframe)', 4);
+        shouldBe('internals.contextLifecycleStateObserverObjectCount(document)', 0);
+        shouldBe('internals.contextLifecycleStateObserverObjectCount(iframe)', 3);
 
         document.body.appendChild(window.iframe.querySelector('video'));
 
@@ -20,8 +20,8 @@
         // but a new one will be created in |document|, so the count is expected
         // to differ by one.
         log('After Reparenting');
-        shouldBe('internals.contextLifecycleStateObserverObjectCount(document)', 4);
-        shouldBe('internals.contextLifecycleStateObserverObjectCount(iframe)', 2);
+        shouldBe('internals.contextLifecycleStateObserverObjectCount(document)', 3);
+        shouldBe('internals.contextLifecycleStateObserverObjectCount(iframe)', 1);
     }
 </script>
 </body>