[Not Ready To Comimt] Add chrome://flags/#enable-off-main-thread-fetch

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 17e33a9223f579b13076fb64634f3ad987a5883d..e840540ef531166ee569a7985561070a614ba9d6 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -101134,6 +101134,7 @@ from previous Chrome versions.
   <int value="223662457" label="BackgroundLoadingForDownloads:enabled"/>
   <int value="243557364" label="ash-force-enable-palette"/>
   <int value="244697230" label="enable-theme-color-in-tabbed-mode"/>
+  <int value="259021228" label="OffMainThreadFetch:disabled"/>
   <int value="262382944" label="GuestViewCrossProcessFrames:disabled"/>
   <int value="266702296" label="disable-plugin-power-saver"/>
   <int value="270267831" label="enable-scripts-require-action"/>
@@ -101565,6 +101566,7 @@ from previous Chrome versions.
   <int value="1951466218" label="enable-data-reduction-proxy-lite-page"/>
   <int value="1955677113" label="trace-export-events-to-etw"/>
   <int value="1958387645" label="ScanCardsInWebPayments:enabled"/>
+  <int value="1959148757" label="OffMainThreadFetch:enabled"/>
   <int value="1960169775" label="NewPhotoPicker:disabled"/>
   <int value="1961425320" label="force-qtkit"/>
   <int value="1964816410" label="AndroidPayIntegrationV2:enabled"/>