Add DataReductionProxyExperimentsStats and UMA for measuring potentially non-compressed bytes.

If no valid Data Reduction Proxy configuration is available to the client,
then the client does not get the benefit of the Data Reduction Proxy during
the period when a configuration is being retrieved. This CL sets up a
configurable simulation where all requests will continue to go through the
Data Reduction Proxy, but if the request is initiated during a period when
the client would request a configuration from the service, we will record
the reduction statistics to determine the overall effect on data compression.

BUG=484864

Review URL: https://codereview.chromium.org/1127893002

Cr-Commit-Position: refs/heads/master@{#330133}

1 files changed, 51 insertions, 0 deletions

diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 1852d3a..8f7329f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -4308,6 +4308,41 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="DataReductionProxy.ConfigFetchLostBytesCL">
+  <owner>jeremyim@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Size of the response body. This is the actual number of bytes received,
+    which usually agrees with but is not necessarily the same as the size
+    specified by the Content-Length header. Only recorded if the request is sent
+    while a simulated Data Reduction Proxy configuration fetch is taking place.
+  </summary>
+</histogram>
+
+<histogram name="DataReductionProxy.ConfigFetchLostBytesDiff">
+  <owner>jeremyim@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The difference between the size specified in the X-Original-Content-Length
+    header and the size of the response body. Only recorded if the request is
+    sent while a simulated Data Reduction Proxy configuration fetch is taking
+    place. Only positive values are logged, so if X-Original-Content-Length is
+    not specified or if it equals or exceeds the content length, it is not
+    logged.
+  </summary>
+</histogram>
+
+<histogram name="DataReductionProxy.ConfigFetchLostBytesOCL">
+  <owner>jeremyim@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Size specified in the X-Original-Content-Length header. If this header is
+    not present in the response, the size of the response body is used. Only
+    recorded if the request is sent while a simulated Data Reduction Proxy
+    configuration fetch is taking place.
+  </summary>
+</histogram>
+
 <histogram
     name="DataReductionProxy.ConfigService.FetchFailedAttemptsBeforeSuccess">
   <owner>jeremyim@chromium.org</owner>
@@ -66682,6 +66717,22 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="DataReductionProxy.BypassedBytes"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="DataReductionProxyConfigFetchLostBytes" separator="_">
+  <suffix name="0" label="Bucket 0 for gathering multiple data points."/>
+  <suffix name="1" label="Bucket 1 for gathering multiple data points."/>
+  <suffix name="2" label="Bucket 2 for gathering multiple data points."/>
+  <suffix name="3" label="Bucket 3 for gathering multiple data points."/>
+  <suffix name="4" label="Bucket 4 for gathering multiple data points."/>
+  <suffix name="5" label="Bucket 5 for gathering multiple data points."/>
+  <suffix name="6" label="Bucket 6 for gathering multiple data points."/>
+  <suffix name="7" label="Bucket 7 for gathering multiple data points."/>
+  <suffix name="8" label="Bucket 8 for gathering multiple data points."/>
+  <suffix name="9" label="Bucket 9 for gathering multiple data points."/>
+  <affected-histogram name="DataReductionProxy.ConfigFetchLostBytesCL"/>
+  <affected-histogram name="DataReductionProxy.ConfigFetchLostBytesDiff"/>
+  <affected-histogram name="DataReductionProxy.ConfigFetchLostBytesOCL"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="DataReductionProxyMissingViaHeaderBytes"
     separator=".">
   <suffix name="4xx" label="Response with 4xx response code"/>