Trigger UMA and fake crash in the presence of an old Finch config

The goal of this CL is to help track down a bug which
might be caused by outdated Finch configs. It uses a fake
crash when it detects this issue to report diagnostics back
to us, and saves some relevant information along with it.
This will not actually crash, only report current state.
It also logs a UMA histogram to get at the Finch seed.

Change-Id: I60c3b4704c9dd2916f9e990d97b56b4209c96e0a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462728
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Auto-Submit: David Schinazi <dschinazi@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817740}

components/network_session_configurator/browser/network_session_configurator.cc

@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "base/command_line.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/feature_list.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
@@ -19,6 +20,7 @@
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
+#include "base/time/time.h"
 #include "build/build_config.h"
 #include "components/network_session_configurator/common/network_features.h"
 #include "components/network_session_configurator/common/network_switches.h"
@@ -458,9 +460,10 @@ size_t GetQuicMaxPacketLength(const VariationParameters& quic_trial_params) {
 
 quic::ParsedQuicVersionVector GetQuicVersions(
     const VariationParameters& quic_trial_params) {
+  std::string trial_versions_str =
+      GetVariationParam(quic_trial_params, "quic_version");
   quic::ParsedQuicVersionVector trial_versions =
-      quic::ParseQuicVersionVectorString(
-          GetVariationParam(quic_trial_params, "quic_version"));
+      quic::ParseQuicVersionVectorString(trial_versions_str);
   const bool obsolete_versions_allowed = base::LowerCaseEqualsASCII(
       GetVariationParam(quic_trial_params, "obsolete_versions_allowed"),
       "true");
@@ -468,12 +471,40 @@ quic::ParsedQuicVersionVector GetQuicVersions(
     quic::ParsedQuicVersionVector filtered_versions;
     quic::ParsedQuicVersionVector obsolete_versions =
         net::ObsoleteQuicVersions();
+    bool found_obsolete_version = false;
     for (const quic::ParsedQuicVersion& version : trial_versions) {
       if (std::find(obsolete_versions.begin(), obsolete_versions.end(),
                     version) == obsolete_versions.end()) {
         filtered_versions.push_back(version);
+      } else {
+        found_obsolete_version = true;
       }
     }
+    if (found_obsolete_version) {
+      UMA_HISTOGRAM_BOOLEAN("Net.QuicSession.FinchObsoleteVersion", true);
+      // OQV prefix stands for Obsolete QUIC Version.
+      static base::debug::CrashKeyString* quic_versions_key =
+          base::debug::AllocateCrashKeyString(
+              "OQV_quic_versions", base::debug::CrashKeySize::Size32);
+      base::debug::ScopedCrashKeyString quic_versions_scoped_key(
+          quic_versions_key, trial_versions_str);
+      static base::debug::CrashKeyString* time_key =
+          base::debug::AllocateCrashKeyString(
+              "OQV_time", base::debug::CrashKeySize::Size32);
+      uint64_t seconds_since_epoch =
+          static_cast<uint64_t>(base::Time::Now().ToDoubleT());
+      seconds_since_epoch = (seconds_since_epoch / 3600) *
+                            3600;  // Only provide granularity of 1h.
+      std::string time_string = base::NumberToString(seconds_since_epoch);
+      base::debug::ScopedCrashKeyString time_scoped_key(time_key, time_string);
+      static base::debug::CrashKeyString* finch_seed_key =
+          base::debug::AllocateCrashKeyString(
+              "OQV_finch_seed", base::debug::CrashKeySize::Size32);
+      std::string finch_seed = variations::GetSeedVersion();
+      base::debug::ScopedCrashKeyString finch_scoped_key(finch_seed_key,
+                                                         finch_seed);
+      base::debug::DumpWithoutCrashing();
+    }
     trial_versions = filtered_versions;
   }
   return trial_versions;

tools/metrics/histograms/histograms_xml/net/histograms.xml

@@ -2787,6 +2787,16 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.FinchObsoleteVersion" enum="Boolean"
+    expires_after="2021-05-11">
+  <owner>dschinazi@chromium.org</owner>
+  <owner>src/net/quic/OWNERS</owner>
+  <summary>
+    Triggered any time Finch configures an obsolete QUIC version. Only recorded
+    when obsolete versions are not allowed (which is the default).
+  </summary>
+</histogram>
+
 <histogram name="Net.QuicSession.FreshDnsResolutionTime" units="ms"
     expires_after="2021-05-11">
   <owner>renjietang@chromium.org</owner>