Loosen FirstMeaningfulPaint UMA network-idle heuristics

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 35bf3ee00b5c96f35104ccaf8a92476c6e6b2fea..10005d80a5ddc1ee97852cf75413c35773f6ea1e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -45463,6 +45463,30 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram
+    name="PageLoad.Experimental.Renderer.FirstMeaningfulPaintDetector.FirstMeaningfulPaintOrdering"
+    enum="FirstMeaningfulPaintOrdering">
+  <owner>ksakamoto@chromium.org</owner>
+  <summary>
+    Whether the two variants of First Meaningful Paint reported different
+    values, and if so, which one was reported first.
+  </summary>
+</histogram>
+
+<histogram
+    name="PageLoad.Experimental.Renderer.FirstMeaningfulPaintDetector.HadNetworkQuiet"
+    enum="NetworkQuietStatus">
+  <owner>ksakamoto@chromium.org</owner>
+  <summary>
+    Recorded when the page load reached network 0-quiet (no active network
+    connection for 0.5 seconds), or network 2-quiet (no more than 2 active
+    network connections for 2 seconds).
+    PageLoad.Experimental.PaintTiming.FirstMeaningfulPaintSignalStatus2
+    histogram gives the fraction of page loads that had network 2-quiet, so it
+    can be used as a baseline.
+  </summary>
+</histogram>
+
 <histogram name="PageLoad.Experimental.TotalRequests.ParseStop"
     units="requests">
   <owner>csharrison@chromium.org</owner>
@@ -94187,6 +94211,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="20" label=".log"/>
 </enum>
 
+<enum name="FirstMeaningfulPaintOrdering" type="int">
+  <int value="0" label="FMP 0-quiet &lt; FMP 2-quiet"/>
+  <int value="1" label="FMP 0-quiet &gt; FMP 2-quiet"/>
+  <int value="2" label="FMP 0-quiet = FMP 2-quiet"/>
+</enum>
+
 <enum name="FirstMeaningfulPaintSignalStatus" type="int">
   <int value="0" label="No input, network active"/>
   <int value="1" label="Had input, network active"/>
@@ -102494,6 +102524,11 @@ from previous Chrome versions.
   <int value="6" label="Channel Type Change"/>
 </enum>
 
+<enum name="NetworkQuietStatus" type="int">
+  <int value="0" label="Had network 0-quiet for 0.5 seconds"/>
+  <int value="1" label="Had network 2-quiet for 2 seconds"/>
+</enum>
+
 <enum name="NetworkSecurityType" type="int">
   <summary>
     The security types come from the connman_service_security enum in