Update image_decoding to use results.AddValue(...)

tools/perf/measurements/image_decoding.py

Index: tools/perf/measurements/image_decoding.py
diff --git a/tools/perf/measurements/image_decoding.py b/tools/perf/measurements/image_decoding.py
index 2ec61c786b1cc30c2663dd8ec9a2640d110cf513..155e6f8bf725c294bcfef4732b62410fc5becad5 100644
--- a/tools/perf/measurements/image_decoding.py
+++ b/tools/perf/measurements/image_decoding.py
@@ -5,6 +5,7 @@
 from metrics import power
 from telemetry.page import page_measurement
 from telemetry.timeline import model
+from telemetry.value import scalar
 
 
 class ImageDecoding(page_measurement.PageMeasurement):
@@ -67,9 +68,11 @@ class ImageDecoding(page_measurement.PageMeasurement):
     assert durations, 'Failed to find "Decode Image" trace events.'
 
     image_decoding_avg = sum(durations) / len(durations)
-    results.Add('ImageDecoding_avg', 'ms', image_decoding_avg)
-    results.Add('ImageLoading_avg', 'ms',
-                tab.EvaluateJavaScript('averageLoadingTimeMs()'))
+    results.AddValue(scalar.ScalarValue(
+        results.current_page, 'ImageDecoding_avg', 'ms', image_decoding_avg))
+    results.AddValue(scalar.ScalarValue(
+        results.current_page, 'ImageLoading_avg', 'ms',
+        tab.EvaluateJavaScript('averageLoadingTimeMs()')))
 
   def CleanUpAfterPage(self, page, tab):
     if tab.browser.is_tracing_running: