Migrate SpeculationsPumpSession to use ElapsedTimer instead of doubles

First things first, SpeculationsPumpSession was storing a base::Time at creation
time to compute an elpased time later on. Using base::TimeTicks is probably
better here since we are not interested in dates but in timestamps.

Since the only purpose of that timestamp is to compute an elapsed time, using a
base::ElapsedTimer seems the perfect fit.

Bug: 979137
Change-Id: Ifbfec4dc9562d79cd0db7d1b158d4acb16c2f1f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1705918Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Sergio Villar <svillar@igalia.com>
Cr-Commit-Position: refs/heads/master@{#678303}

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

@@ -37,13 +37,12 @@ namespace blink {
 
 SpeculationsPumpSession::SpeculationsPumpSession(unsigned& nesting_level)
     : NestingLevelIncrementer(nesting_level),
-      start_time_(CurrentTime()),
       processed_element_tokens_(0) {}
 
 SpeculationsPumpSession::~SpeculationsPumpSession() = default;
 
-inline double SpeculationsPumpSession::ElapsedTime() const {
-  return CurrentTime() - start_time_;
+inline base::TimeDelta SpeculationsPumpSession::ElapsedTime() const {
+  return start_time_.Elapsed();
 }
 
 void SpeculationsPumpSession::AddedElementTokens(size_t count) {
@@ -103,7 +102,8 @@ inline bool HTMLParserScheduler::ShouldYield(
   if (ThreadScheduler::Current()->ShouldYieldForHighPriorityWork())
     return true;
 
-  const double kParserTimeLimit = 0.5;
+  const base::TimeDelta kParserTimeLimit =
+      base::TimeDelta::FromMilliseconds(500);
   if (session.ElapsedTime() > kParserTimeLimit)
     return true;
 

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

@@ -29,6 +29,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_refptr.h"
 #include "base/single_thread_task_runner.h"
+#include "base/timer/elapsed_timer.h"
 #include "third_party/blink/renderer/core/html/parser/nesting_level_incrementer.h"
 #include "third_party/blink/renderer/platform/scheduler/public/post_cancellable_task.h"
 #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
@@ -44,12 +45,12 @@ class SpeculationsPumpSession : public NestingLevelIncrementer {
   SpeculationsPumpSession(unsigned& nesting_level);
   ~SpeculationsPumpSession();
 
-  double ElapsedTime() const;
+  base::TimeDelta ElapsedTime() const;
   void AddedElementTokens(size_t count);
   size_t ProcessedElementTokens() const { return processed_element_tokens_; }
 
  private:
-  double start_time_;
+  base::ElapsedTimer start_time_;
   size_t processed_element_tokens_;
 };