Filter out any non-standard WebRTC stats members.

Instead of using a whitelist, which is how non-standard stats objects
are being filtered out, this uses an "is_standardized" method on
RTCStatsMemberInterface.

This will allow us to easily add non-standard stats to WebRTC (or mark
previously non-standardized stats as standardized) without needing to
update chromium as well every time.

Follow up to:
https://webrtc-review.googlesource.com/c/src/+/83743

Bug: webrtc:9410
Change-Id: Idd349fedf30aa15db7c6e101115a1171aef33b4f
Reviewed-on: https://chromium-review.googlesource.com/1121319Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571861}

content/renderer/media/webrtc/rtc_stats.cc

@@ -4,6 +4,7 @@
 
 #include "content/renderer/media/webrtc/rtc_stats.h"
 
+#include <algorithm>
 #include <set>
 #include <string>
 
@@ -57,6 +58,22 @@ bool IsWhitelistedStats(const webrtc::RTCStats& stats) {
   return GetStatsWhitelist()->IsWhitelisted(stats);
 }
 
+// Filters out any unstandardized members; stats should only be surfaced to JS
+// if they're standardized.
+std::vector<const webrtc::RTCStatsMemberInterface*> StandardizedMembers(
+    std::vector<const webrtc::RTCStatsMemberInterface*> stats_members) {
+  // Note that using "is_standarized" avoids having to maintain a whitelist of
+  // every single standardized member, as we do at the "stats object" level
+  // with "RTCStatsWhitelist".
+  stats_members.erase(
+      std::remove_if(stats_members.begin(), stats_members.end(),
+                     [](const webrtc::RTCStatsMemberInterface* member) {
+                       return !member->is_standardized();
+                     }),
+      stats_members.end());
+  return stats_members;
+}
+
 }  // namespace
 
 RTCStatsReport::RTCStatsReport(
@@ -105,7 +122,7 @@ RTCStats::RTCStats(
     const webrtc::RTCStats* stats)
     : stats_owner_(stats_owner),
       stats_(stats),
-      stats_members_(stats->Members()) {
+      stats_members_(StandardizedMembers(stats->Members())) {
   DCHECK(stats_owner_);
   DCHECK(stats_);
   DCHECK(stats_owner_->Get(stats_->id()));

content/renderer/media/webrtc/rtc_stats.h

@@ -15,6 +15,9 @@
 
 namespace content {
 
+// Wrapper around a webrtc::RTCStatsReport that also filters out any stats
+// objects that aren't whitelisted, and any members that aren't standardized
+// (using RTCStatsMemberInterface::is_standardized).
 class CONTENT_EXPORT RTCStatsReport : public blink::WebRTCStatsReport {
  public:
   RTCStatsReport(

content/renderer/media/webrtc/rtc_stats_unittest.cc

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <memory>
+
 #include "content/renderer/media/webrtc/rtc_stats.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
@@ -45,4 +47,47 @@ TEST(RTCStatsTest, OnlyIncludeWhitelistedStats_Iteration) {
   EXPECT_FALSE(report.Next());
 }
 
+// Stats object with both a standard and non-standard member, used for the test
+// below.
+namespace {
+class TestStats : public webrtc::RTCStats {
+ public:
+  WEBRTC_RTCSTATS_DECL();
+
+  TestStats(const std::string& id, int64_t timestamp_us);
+  ~TestStats() override = default;
+
+  webrtc::RTCStatsMember<int32_t> standardized;
+  webrtc::RTCNonStandardStatsMember<int32_t> non_standardized;
+};
+
+WEBRTC_RTCSTATS_IMPL(TestStats,
+                     webrtc::RTCStats,
+                     "teststats",
+                     &standardized,
+                     &non_standardized);
+
+TestStats::TestStats(const std::string& id, int64_t timestamp_us)
+    : RTCStats(id, timestamp_us),
+      standardized("standardized"),
+      non_standardized("non_standardized") {}
+}  // namespace
+
+// Similar to how only whitelisted stats objects should be surfaced, only
+// standardized members of the whitelisted objects should be surfaced.
+TEST(RTCStatsTest, OnlyIncludeStandarizedMembers) {
+  rtc::scoped_refptr<webrtc::RTCStatsReport> webrtc_report =
+      webrtc::RTCStatsReport::Create(42);
+  WhitelistStatsForTesting(TestStats::kType);
+  webrtc_report->AddStats(std::make_unique<TestStats>("id", 0));
+
+  // TestStats has two members, but the non-standard member should be filtered
+  // out.
+  RTCStatsReport report(webrtc_report.get());
+  std::unique_ptr<blink::WebRTCStats> stats = report.Next();
+  ASSERT_NE(nullptr, stats);
+  ASSERT_EQ(1u, stats->MembersCount());
+  EXPECT_EQ("standardized", stats->GetMember(0)->GetName());
+}
+
 }  // namespace content