Use TaskRunnerTimer in FontMatchingMetrics

This should improve performance when fonts are quickly cycled as the
repeated calls to Time::Now() were (somewhat) slow.

Bug: 1110204
Change-Id: I861288f9470157cc349e41a0e124c95cba6a381a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333378
Commit-Queue: Alex Turner <alexmt@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796986}

third_party/blink/renderer/core/dom/document.cc

@@ -7118,7 +7118,8 @@ FontMatchingMetrics* Document::GetFontMatchingMetrics() {
   if (font_matching_metrics_)
     return font_matching_metrics_.get();
   font_matching_metrics_ = std::make_unique<FontMatchingMetrics>(
-      IsInMainFrame(), UkmRecorder(), UkmSourceID());
+      IsInMainFrame(), UkmRecorder(), UkmSourceID(),
+      GetTaskRunner(TaskType::kInternalDefault));
   return font_matching_metrics_.get();
 }
 

third_party/blink/renderer/platform/fonts/DEPS

@@ -21,6 +21,7 @@ include_rules = [
     "+third_party/blink/renderer/platform/wtf/shared_buffer.h",
     "+third_party/blink/renderer/platform/testing",
     "+third_party/blink/renderer/platform/text",
+    "+third_party/blink/renderer/platform/timer.h",
     "+third_party/blink/renderer/platform/web_test_support.h",
     "+third_party/blink/renderer/platform/wtf",
     "+ui/base/mojom/attributed_string.mojom-blink.h",

third_party/blink/renderer/platform/fonts/font_matching_metrics.cc

@@ -28,12 +28,18 @@ HashSet<T> SetIntersection(const HashSet<T>& a, const HashSet<T>& b) {
 
 namespace blink {
 
-FontMatchingMetrics::FontMatchingMetrics(bool top_level,
-                                         ukm::UkmRecorder* ukm_recorder,
-                                         ukm::SourceId source_id)
+FontMatchingMetrics::FontMatchingMetrics(
+    bool top_level,
+    ukm::UkmRecorder* ukm_recorder,
+    ukm::SourceId source_id,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : top_level_(top_level),
       ukm_recorder_(ukm_recorder),
-      source_id_(source_id) {
+      source_id_(source_id),
+      identifiability_metrics_timer_(
+          task_runner,
+          this,
+          &FontMatchingMetrics::IdentifiabilityMetricsTimerFired) {
   // Estimate of average page font use from anecdotal browsing session.
   constexpr unsigned kEstimatedFontCount = 7;
   local_fonts_succeeded_.ReserveCapacityForSize(kEstimatedFontCount);
@@ -182,16 +188,14 @@ void FontMatchingMetrics::PublishUkmMetrics() {
 }
 
 void FontMatchingMetrics::OnFontLookup() {
-  if (!time_of_earliest_unpublished_font_lookup_) {
-    time_of_earliest_unpublished_font_lookup_ = base::Time::Now();
-    return;
+  if (!identifiability_metrics_timer_.IsActive()) {
+    identifiability_metrics_timer_.StartOneShot(base::TimeDelta::FromMinutes(1),
+                                                FROM_HERE);
   }
+}
 
-  if (base::Time::Now() - *time_of_earliest_unpublished_font_lookup_ >=
-      base::TimeDelta::FromMinutes(1)) {
-    PublishIdentifiabilityMetrics();
-    time_of_earliest_unpublished_font_lookup_ = base::Time::Now();
-  }
+void FontMatchingMetrics::IdentifiabilityMetricsTimerFired(TimerBase*) {
+  PublishIdentifiabilityMetrics();
 }
 
 void FontMatchingMetrics::PublishAllMetrics() {

third_party/blink/renderer/platform/fonts/font_matching_metrics.h

@@ -12,6 +12,7 @@
 #include "third_party/blink/renderer/platform/fonts/font_description.h"
 #include "third_party/blink/renderer/platform/fonts/simple_font_data.h"
 #include "third_party/blink/renderer/platform/platform_export.h"
+#include "third_party/blink/renderer/platform/timer.h"
 #include "third_party/blink/renderer/platform/wtf/hash_set.h"
 #include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
 #include "third_party/blink/renderer/platform/wtf/text/atomic_string_hash.h"
@@ -161,7 +162,8 @@ class PLATFORM_EXPORT FontMatchingMetrics {
  public:
   FontMatchingMetrics(bool top_level,
                       ukm::UkmRecorder* ukm_recorder,
-                      ukm::SourceId source_id);
+                      ukm::SourceId source_id,
+                      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   // Called when a page attempts to match a font family, and the font family is
   // available.
@@ -232,6 +234,8 @@ class PLATFORM_EXPORT FontMatchingMetrics {
   void PublishUkmMetrics();
 
  private:
+  void IdentifiabilityMetricsTimerFired(TimerBase*);
+
   // Get a hash that uniquely represents the font data. Returns 0 if |font_data|
   // is nullptr.
   uint64_t GetHashForFontData(SimpleFontData* font_data);
@@ -272,9 +276,7 @@ class PLATFORM_EXPORT FontMatchingMetrics {
   ukm::UkmRecorder* const ukm_recorder_;
   const ukm::SourceId source_id_;
 
-  // Records when the first font lookup occurred since the last call to
-  // PublishIdentifiablityMetrics(), if any.
-  base::Optional<base::Time> time_of_earliest_unpublished_font_lookup_;
+  TaskRunnerTimer<FontMatchingMetrics> identifiability_metrics_timer_;
 };
 
 }  // namespace blink