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 5c6e5f064972efa351af93e0297c5b190bcacc07..53bacd41f007a378906316f85096f9e618552323 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -100961,6 +100961,7 @@ 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"/>
@@ -101555,6 +101556,7 @@ 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"/>