Precache tracking database

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 06171d6ef76ad0e59058966a475f5d5a7e2b7c7b..0f9708bab4afb780e71685de6f456bbd8d853ee0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -13805,6 +13805,58 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Precache.DailyDownloadedNonPrecacheKB" units="KB">
+  <summary>
+    The number of kilobytes that were downloaded over the network for HTTP/HTTPS
+    fetches that were not motivated by precaching. This metric is accumulated
+    for each profile over 24 hour intervals, and can cover multiple sessions.
+    Values of this metric for previous, unreported 24 hour intervals are
+    reported at the start of a precaching cycle. 24 hour intervals where
+    Precache.DailyDownloadedNonPrecacheKB,
+    Precache.DailyDownloadedPrecacheMotivatedKB, and Precache.DailySavedKB would
+    all be 0 for a profile are not reported.
+  </summary>
+</histogram>
+
+<histogram name="Precache.DailyDownloadedPrecacheMotivatedKB" units="KB">
+  <summary>
+    The number of kilobytes that were downloaded because of precaching. This
+    metric is accumulated for each profile over 24 hour intervals, and can cover
+    multiple sessions. Values of this metric for previous, unreported 24 hour
+    intervals are reported at the start of a precaching cycle. 24 hour intervals
+    where Precache.DailyDownloadedNonPrecacheKB,
+    Precache.DailyDownloadedPrecacheMotivatedKB, and Precache.DailySavedKB would
+    all be 0 for a profile are not reported.
+  </summary>
+</histogram>
+
+<histogram name="Precache.DailySavedKB" units="KB">
+  <summary>
+    The number of kilobytes during user browsing that were served from the
+    cache, but would have been downloaded over a network if precaching was
+    disabled. This metric is accumulated for each profile over 24 hour
+    intervals, and can cover multiple sessions. Values of this metric for
+    previous, unreported 24 hour intervals are reported at the start of a
+    precaching cycle. 24 hour intervals where
+    Precache.DailyDownloadedNonPrecacheKB,
+    Precache.DailyDownloadedPrecacheMotivatedKB, and Precache.DailySavedKB would
+    all be 0 for a profile are not reported.
+  </summary>
+</histogram>
+
+<histogram name="Precache.DailySavingsPercentage" units="%">
+  <summary>
+    The percentage of user browsing network bandwidth that was saved because of
+    precaching. This metric is accumulated for each profile over 24 hour
+    intervals, and can cover multiple sessions. Values of this metric for
+    previous, unreported 24 hour intervals are reported at the start of a
+    precaching cycle. 24 hour intervals where
+    Precache.DailyDownloadedNonPrecacheKB,
+    Precache.DailyDownloadedPrecacheMotivatedKB, and Precache.DailySavedKB would
+    all be 0 for a profile are not reported.
+  </summary>
+</histogram>
+
 <histogram name="Prerender.Events" enum="PrerenderHoverEvent">
   <obsolete>
     deprecated May 10 2012
@@ -31733,6 +31785,14 @@ other types of suffix sets.
   <affected-histogram name="Plugin.PpapiPluginLoadResult"/>
 </fieldtrial>
 
+<fieldtrial name="PrecacheCellular" separator=".">
+  <group name="Cellular"
+      label="covers fetches when connected to cellular networks"/>
+  <affected-histogram name="Precache.DailyDownloadedNonPrecacheKB"/>
+  <affected-histogram name="Precache.DailySavedKB"/>
+  <affected-histogram name="Precache.DailySavingsPercentage"/>
+</fieldtrial>
+
 <fieldtrial name="Prefetch">
   <group name="ContentPrefetchPrefetchOff"
       label="Prefetch is completely disabled."/>