Allow base::ElapsedTimer use in Blink

ElapsedTimer is a small useful utility class for measuring time.
As a wise Greek may put it: "The unmeasured time is not worth having".

Here is discussion that inspired this CL: https://chromium-review.googlesource.com/c/chromium/src/+/951922#message-fca340ea66b052ad7ee1d6e92d42b61ac549456d

Change-Id: Iebd3d49c1965fd0b1a16ad0eeee7af302a6afbf3
Reviewed-on: https://chromium-review.googlesource.com/c/1295177Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Majid Valipour <majidvp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601896}

third_party/blink/renderer/DEPS

@@ -31,6 +31,7 @@ include_rules = [
     "+base/thread_annotations.h",
     "+base/threading/thread_checker.h",
     "+base/time/time.h",
+    "+base/timer/elapsed_timer.h",
     "+build",
     "+services/service_manager/public/cpp/connector.h",
     "+services/service_manager/public/cpp/interface_provider.h",

third_party/blink/renderer/modules/animationworklet/animation_worklet_global_scope.cc

@@ -5,6 +5,7 @@
 #include "third_party/blink/renderer/modules/animationworklet/animation_worklet_global_scope.h"
 
 #include "base/metrics/histogram_macros.h"
+#include "base/timer/elapsed_timer.h"
 #include "third_party/blink/renderer/bindings/core/v8/serialization/serialized_script_value.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_object_parser.h"
 #include "third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.h"
@@ -80,7 +81,7 @@ Animator* AnimationWorkletGlobalScope::CreateAnimatorFor(
 
 std::unique_ptr<AnimationWorkletOutput> AnimationWorkletGlobalScope::Mutate(
     const AnimationWorkletInput& mutator_input) {
-  base::TimeTicks start_time = CurrentTimeTicks();
+  base::ElapsedTimer timer;
   DCHECK(IsContextThread());
 
   ScriptState* script_state = ScriptController()->GetScriptState();
@@ -135,8 +136,8 @@ std::unique_ptr<AnimationWorkletOutput> AnimationWorkletGlobalScope::Mutate(
   }
 
   UMA_HISTOGRAM_CUSTOM_MICROSECONDS_TIMES(
-      "Animation.AnimationWorklet.GlobalScope.MutateDuration",
-      CurrentTimeTicks() - start_time, base::TimeDelta::FromMicroseconds(1),
+      "Animation.AnimationWorklet.GlobalScope.MutateDuration", timer.Elapsed(),
+      base::TimeDelta::FromMicroseconds(1),
       base::TimeDelta::FromMilliseconds(100), 50);
 
   return result;

third_party/blink/tools/blinkpy/presubmit/audit_non_blink_usage.py

@@ -32,6 +32,7 @@ _CONFIG = [
             # //base constructs that are allowed everywhere
             'base::AdoptRef',
             'base::AutoReset',
+            'base::ElapsedTimer',
             'base::File',
             'base::FilePath',
             'base::GetUniqueIdForProcess',