Enable HistogramName interning

This change depends on
https://android-review.googlesource.com/c/platform/external/perfetto/+/1438933

Bug: 1119834
Change-Id: I55bc44de601479704fd35c2f12ccad2459a61fb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2431566Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Mikhail Khokhlov <khokhlov@google.com>
Commit-Queue: Julia Semavina <nuwanda@google.com>
Cr-Commit-Position: refs/heads/master@{#813810}

services/tracing/public/cpp/perfetto/trace_event_data_source.cc

@@ -49,6 +49,7 @@
 #include "third_party/perfetto/include/perfetto/ext/tracing/core/shared_memory_arbiter.h"
 #include "third_party/perfetto/include/perfetto/ext/tracing/core/trace_writer.h"
 #include "third_party/perfetto/include/perfetto/tracing/track.h"
+#include "third_party/perfetto/include/perfetto/tracing/track_event_interned_data_index.h"
 #include "third_party/perfetto/protos/perfetto/trace/chrome/chrome_metadata.pbzero.h"
 #include "third_party/perfetto/protos/perfetto/trace/chrome/chrome_trace_event.pbzero.h"
 #include "third_party/perfetto/protos/perfetto/trace/trace_packet.pbzero.h"
@@ -1041,6 +1042,24 @@ void TraceEventDataSource::FlushCurrentThread() {
   }
 }
 
+namespace {
+
+struct InternedHistogramName
+    : public perfetto::TrackEventInternedDataIndex<
+          InternedHistogramName,
+          perfetto::protos::pbzero::InternedData::kHistogramNamesFieldNumber,
+          std::string> {
+  static void Add(perfetto::protos::pbzero::InternedData* interned_data,
+                  size_t iid,
+                  const std::string& histogram_name) {
+    auto* msg = interned_data->add_histogram_names();
+    msg->set_iid(iid);
+    msg->set_name(histogram_name);
+  }
+};
+
+}  // namespace
+
 // static
 void TraceEventDataSource::OnMetricsSampleCallback(
     const char* histogram_name,
@@ -1056,7 +1075,8 @@ void TraceEventDataSource::OnMetricsSampleCallback(
         new_sample->set_name_hash(name_hash);
         new_sample->set_sample(sample);
         if (!privacy_filtering_enabled) {
-          new_sample->set_name(histogram_name);
+          size_t iid = InternedHistogramName::Get(&ctx, histogram_name);
+          new_sample->set_name_iid(iid);
         }
       });
 }

services/tracing/public/cpp/perfetto/trace_event_data_source_unittest.cc

@@ -1917,9 +1917,11 @@ TEST_F(TraceEventDataSourceTest, HistogramSampleTraceConfigEmpty) {
                         {{1u, TRACE_DISABLED_BY_DEFAULT("histogram_samples")}});
   ExpectEventNames(e_packet, {{1u, "HistogramSample"}});
   ASSERT_TRUE(e_packet->track_event().has_chrome_histogram_sample());
-  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_hash(),
-            base::HashMetricName("Foo.Bar"));
   EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().sample(), 1u);
+  ASSERT_TRUE(e_packet->has_interned_data());
+  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_iid(),
+            e_packet->interned_data().histogram_names()[0].iid());
+  EXPECT_EQ(e_packet->interned_data().histogram_names()[0].name(), "Foo.Bar");
 }
 
 TEST_F(TraceEventDataSourceTest, HistogramSampleTraceConfigNotEmpty) {
@@ -1946,9 +1948,11 @@ TEST_F(TraceEventDataSourceTest, HistogramSampleTraceConfigNotEmpty) {
   ASSERT_TRUE(e_packet->track_event().has_chrome_histogram_sample());
   EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_hash(),
             base::HashMetricName("Foo1.Bar1"));
-  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name(),
-            "Foo1.Bar1");
   EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().sample(), 1u);
+  ASSERT_TRUE(e_packet->has_interned_data());
+  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_iid(),
+            e_packet->interned_data().histogram_names()[0].iid());
+  EXPECT_EQ(e_packet->interned_data().histogram_names()[0].name(), "Foo1.Bar1");
 
   e_packet = producer_client()->GetFinalizedPacket(packet_index++);
 
@@ -1957,9 +1961,11 @@ TEST_F(TraceEventDataSourceTest, HistogramSampleTraceConfigNotEmpty) {
   ASSERT_TRUE(e_packet->track_event().has_chrome_histogram_sample());
   EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_hash(),
             base::HashMetricName("Foo3.Bar3"));
-  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name(),
-            "Foo3.Bar3");
   EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().sample(), 1u);
+  ASSERT_TRUE(e_packet->has_interned_data());
+  EXPECT_EQ(e_packet->track_event().chrome_histogram_sample().name_iid(),
+            e_packet->interned_data().histogram_names()[0].iid());
+  EXPECT_EQ(e_packet->interned_data().histogram_names()[0].name(), "Foo3.Bar3");
 
   EXPECT_EQ(packet_index, producer_client()->GetFinalizedPacketCount());
 }