Allow for pausing background tabs on desktop via about:flags.

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 cdef8acfc8d9de2540e7f568210dd7db4f3d987d..39b31a6bdc4c234a3f71e953e3eaa262323d960c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -101080,6 +101080,7 @@ from previous Chrome versions.
   <int value="-1772172557" label="enable-osk-overscroll"/>
   <int value="-1767470652" label="out-of-process-pdf"/>
   <int value="-1751928267" label="disable-icon-ntp"/>
+  <int value="-1749176684" label="PauseBackgroundTabs:disabled"/>
   <int value="-1746767834" label="ssl-interstitial-v2-gray"/>
   <int value="-1740519217" label="disable-software-rasterizer"/>
   <int value="-1735643253" label="enable-display-list-2d-canvas"/>
@@ -101107,6 +101108,7 @@ from previous Chrome versions.
   <int value="-1660972490" label="gpu-rasterization-msaa-sample-count"/>
   <int value="-1655535052" label="enable-pointer-events"/>
   <int value="-1654344175" label="disable-extension-info-dialog"/>
+  <int value="-1653838003" label="PauseBackgroundTabs:enabled"/>
   <int value="-1649778035" label="disable-clear-browsing-data-counters"/>
   <int value="-1648216169" label="NewOmniboxAnswerTypes:disabled"/>
   <int value="-1634154256" label="ZeroSuggestRedirectToChrome:enabled"/>