[HBD] Add flag in about:flags for PPS on ALLOW mode.

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 94c5dd08df57d819c36d199e73ee8b0ccecfb9be..0c942e8794366182637e713a11cc8e2e3b24e6ef 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -87063,6 +87063,7 @@ value.
   <int value="-1578295753" label="UserMediaScreenCapturing:disabled"/>
   <int value="-1572010356" label="enable-privet-v3"/>
   <int value="-1571841513" label="enable-devtools-experiments"/>
+  <int value="-1559789642" label="RunAllFlashInAllowMode:enabled"/>
   <int value="-1553477903" label="ash-disable-text-filtering-in-overview-mode"/>
   <int value="-1546903171" label="enable-touch-drag-drop"/>
   <int value="-1514943439" label="ash-enable-swipe-to-close-in-overview-mode"/>
@@ -87440,6 +87441,7 @@ value.
   <int value="470011024" label="NonValidatingReloadOnNormalReload:enabled"/>
   <int value="474743272" label="material-design-ink-drop"/>
   <int value="477967119" label="enable-unified-media-pipeline"/>
+  <int value="479906041" label="RunAllFlashInAllowMode:disabled"/>
   <int value="480544447" label="NonValidatingReloadOnRefreshContentV2:enabled"/>
   <int value="493903641" label="disable-appcontainer"/>
   <int value="494733611" label="disable-drop-sync-credential"/>