From d3b510ca27134ea7ac6d1ab37e7123d9289f22a0 Mon Sep 17 00:00:00 2001
From: rdsmith <rdsmith@chromium.org>
Date: Thu, 4 Feb 2016 15:13:15 -0800
Subject: [PATCH] Log what filter causes a decoding error.

BUG=584326
R=xunjieli@chromium.org

Review URL: https://codereview.chromium.org/1670643003

Cr-Commit-Position: refs/heads/master@{#373651}
---
 net/filter/filter.cc                    |  2 ++
 net/filter/filter.h                     |  7 ++++++-
 net/url_request/url_request_job.cc      |  2 ++
 tools/metrics/histograms/histograms.xml | 21 +++++++++++++++++++++
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/net/filter/filter.cc b/net/filter/filter.cc
index 466aa109fd70b7..502ce5bb5d7742 100644
--- a/net/filter/filter.cc
+++ b/net/filter/filter.cc
@@ -78,6 +78,8 @@ std::string FilterTypeAsString(Filter::FilterType type_id) {
       return "FILTER_TYPE_SDCH_POSSIBLE  ";
     case Filter::FILTER_TYPE_UNSUPPORTED:
       return "FILTER_TYPE_UNSUPPORTED";
+    case Filter::FILTER_TYPE_MAX:
+      return "FILTER_TYPE_MAX";
   }
   return "";
 }
diff --git a/net/filter/filter.h b/net/filter/filter.h
index e9df3dbc9dbc65..31d08d4980fc48 100644
--- a/net/filter/filter.h
+++ b/net/filter/filter.h
@@ -151,7 +151,8 @@ class NET_EXPORT_PRIVATE Filter {
     FILTER_ERROR
   };
 
-  // Specifies type of filters that can be created.
+  // Specifies type of filters that can be created.  Do not change the values
+  // of this enum; it is preserved in a histogram.
   enum FilterType {
     FILTER_TYPE_BROTLI,
     FILTER_TYPE_DEFLATE,
@@ -160,6 +161,8 @@ class NET_EXPORT_PRIVATE Filter {
     FILTER_TYPE_SDCH,
     FILTER_TYPE_SDCH_POSSIBLE,  // Sdch possible, but pass through allowed.
     FILTER_TYPE_UNSUPPORTED,
+
+    FILTER_TYPE_MAX
   };
 
   virtual ~Filter();
@@ -233,6 +236,8 @@ class NET_EXPORT_PRIVATE Filter {
   // Returns a string describing the FilterTypes implemented by this filter.
   std::string OrderedFilterList() const;
 
+  FilterType type() const { return type_id_; }
+
  protected:
   friend class BrotliUnitTest;
   friend class GZipUnitTest;
diff --git a/net/url_request/url_request_job.cc b/net/url_request/url_request_job.cc
index 7ceff553d748a8..cbefc9e3f06845 100644
--- a/net/url_request/url_request_job.cc
+++ b/net/url_request/url_request_job.cc
@@ -749,6 +749,8 @@ Error URLRequestJob::ReadFilteredData(int* bytes_read) {
                    << " Filter Error";
           filter_needs_more_output_space_ = false;
           error = ERR_CONTENT_DECODING_FAILED;
+          UMA_HISTOGRAM_ENUMERATION("Net.ContentDecodingFailed.FilterType",
+                                    filter_->type(), Filter::FILTER_TYPE_MAX);
           break;
         }
         default: {
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 100e02afdb3a74..6b9b776376510c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -23390,6 +23390,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.ContentDecodingFailed.FilterType" enum="NetFilterType">
+  <owner>rdsmith@chromium.org</owner>
+  <summary>
+    For each CONTENT_DECODING_FAILED, record the filter that failed.
+  </summary>
+</histogram>
+
 <histogram name="net.CookieBackingStoreUpdateResults"
     enum="BackingStoreResults">
   <obsolete>
@@ -72609,6 +72616,20 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="21" label="Show Offline Copy Button Clicked"/>
 </enum>
 
+<enum name="NetFilterType" type="int">
+  <summary>
+    Specific content decoding filter.  See   net::Filter::FilterType for more
+    details
+  </summary>
+  <int value="0" label="Brotli"/>
+  <int value="1" label="Deflate"/>
+  <int value="2" label="GZIP"/>
+  <int value="3" label="GzipHelpingSdch"/>
+  <int value="4" label="SDCH"/>
+  <int value="5" label="SDCHPossible"/>
+  <int value="6" label="Unsupported"/>
+</enum>
+
 <enum name="NetInternalsUiFeature" type="int">
   <int value="0" label="NetInternals"/>
   <int value="1" label="Connection tester"/>