Get signals working in the EXTRA_DATA section of MHTML

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 ed085024e24521eec26a45d9d1327ecc03711c8c..d02b00951bffd84dc14a2c115ef248518f12bf10 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -100009,6 +100009,7 @@ from previous Chrome versions.
   <int value="-1985025593" label="file-manager-enable-new-gallery"/>
   <int value="-1980328793" label="trace-upload-url"/>
   <int value="-1972383451" label="disable-pinch"/>
+  <int value="-1972312724" label="OfflinePagesLoadSignalCollecting:enabled"/>
   <int value="-1972219399" label="NTPSaveToOffline:enabled"/>
   <int value="-1971086581" label="print-scaling"/>
   <int value="-1963427770" label="EmojiHandwritingVoiceInput:disabled"/>
@@ -100589,6 +100590,7 @@ from previous Chrome versions.
   <int value="431691805" label="MediaDocumentDownloadButton:enabled"/>
   <int value="446316019" label="enable-threaded-compositing"/>
   <int value="451196246" label="disable-impl-side-painting"/>
+  <int value="453102772" label="OfflinePagesLoadSignalCollecting:disabled"/>
   <int value="455698038"
       label="disable-gesture-requirement-for-media-playback"/>
   <int value="457881889" label="enable-autoplay-muted-videos"/>