Remove unnecessary call to base::UkmSourceId::FromInt64.

Change-Id: I621327ca4c1c1c992e4e9d55abc406096266fa19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2210483Reviewed-by: Asanka Herath <asanka@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@google.com>
Cr-Commit-Position: refs/heads/master@{#771808}

third_party/blink/renderer/core/html/canvas/html_canvas_element.cc

@@ -256,8 +256,7 @@ void HTMLCanvasElement::RegisterRenderingContextFactory(
 void HTMLCanvasElement::RecordIdentifiabilityMetric(
     const blink::IdentifiableSurface& surface,
     int64_t value) const {
-  blink::IdentifiabilityMetricBuilder(
-      base::UkmSourceId::FromInt64(GetDocument().UkmSourceID()))
+  blink::IdentifiabilityMetricBuilder(GetDocument().UkmSourceID())
       .Set(surface, value)
       .Record(GetDocument().UkmRecorder());
 }