UMA for data reduction proxy probe net errors

Added UMA to report the type of net error that occurred
when the data reduction proxy probe failed due to a
network error. Note the probe can also fail due to
the response being modified, which this UMA does not
track.

BUG=397256

Review URL: https://codereview.chromium.org/417253002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285711 0039d316-1c4b-4281-b951-d872f2087c98

components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc

@@ -8,6 +8,7 @@
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/prefs/pref_member.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
@@ -53,6 +54,9 @@ const char kUMAProxyStartupStateHistogram[] =
 // Key of the UMA DataReductionProxy.ProbeURL histogram.
 const char kUMAProxyProbeURL[] = "DataReductionProxy.ProbeURL";
 
+// Key of the UMA DataReductionProxy.ProbeURLNetError histogram.
+const char kUMAProxyProbeURLNetError[] = "DataReductionProxy.ProbeURLNetError";
+
 // Record a network change event.
 void RecordNetworkChangeEvent(DataReductionProxyNetworkChangeEvent event) {
   UMA_HISTOGRAM_ENUMERATION("DataReductionProxy.NetworkChangeEvents",
@@ -234,10 +238,16 @@ void DataReductionProxySettings::OnURLFetchComplete(
 
   DCHECK(source == fetcher_.get());
   net::URLRequestStatus status = source->GetStatus();
-  if (status.status() == net::URLRequestStatus::FAILED &&
-      status.error() == net::ERR_INTERNET_DISCONNECTED) {
-    RecordProbeURLFetchResult(INTERNET_DISCONNECTED);
-    return;
+  if (status.status() == net::URLRequestStatus::FAILED) {
+    if (status.error() == net::ERR_INTERNET_DISCONNECTED) {
+      RecordProbeURLFetchResult(INTERNET_DISCONNECTED);
+      return;
+    }
+    // TODO(bengr): Remove once we understand the reasons probes are failing.
+    // Probe errors are either due to fetcher-level errors or modified
+    // responses. This only tracks the former.
+    UMA_HISTOGRAM_SPARSE_SLOWLY(
+        kUMAProxyProbeURLNetError, std::abs(status.error()));
   }
 
   std::string response;

tools/metrics/histograms/histograms.xml

@@ -3177,6 +3177,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="DataReductionProxy.ProbeURLNetError" enum="NetErrorCodes">
+  <owner>bengr@chromium.org</owner>
+  <owner>megjablon@chromium.org</owner>
+  <summary>
+    Reports the type of network error when the data reduction proxy probe fails
+    due to a network error.
+  </summary>
+</histogram>
+
 <histogram name="DataReductionProxy.PromoAction"
     enum="DataReductionProxyPromoAction">
   <owner>bengr@chromium.org</owner>