Change the logic for discarding all non-histogram logs because of actions/omnibox events to truncat…

components/metrics/metrics_log.cc

Index: components/metrics/metrics_log.cc
diff --git a/components/metrics/metrics_log.cc b/components/metrics/metrics_log.cc
index ac35ce396a32a8f06f1a7a7d913953cbb161e290..a9f2fe6109dac4aa24c288d6536dd055a0e4cb18 100644
--- a/components/metrics/metrics_log.cc
+++ b/components/metrics/metrics_log.cc
@@ -42,6 +42,12 @@ typedef variations::ActiveGroupId ActiveGroupId;
 
 namespace metrics {
 
+namespace internal {
+// Maximum number of events before truncation.
+extern const int kOmniboxEventLimit = 5000;
+extern const int kUserActionEventLimit = 5000;
+}
+
 namespace {
 
 // Any id less than 16 bytes is considered to be a testing id.
@@ -323,6 +329,25 @@ void MetricsLog::CloseLog() {
   closed_ = true;
 }
 
+void MetricsLog::TruncateEvents() {
+  DCHECK(!closed_);
+  if (uma_proto_.user_action_event_size() > internal::kUserActionEventLimit) {
+    UMA_HISTOGRAM_COUNTS_100000("UMA.TruncatedEvents.UserAction",
+                                uma_proto_.user_action_event_size());
+    uma_proto_.mutable_user_action_event()->DeleteSubrange(
+        internal::kUserActionEventLimit,
+        uma_proto_.user_action_event_size() - internal::kUserActionEventLimit);
+  }
+
+  if (uma_proto_.omnibox_event_size() > internal::kOmniboxEventLimit) {
+    UMA_HISTOGRAM_COUNTS_100000("UMA.TruncatedEvents.Omnibox",
+                                uma_proto_.omnibox_event_size());
+    uma_proto_.mutable_omnibox_event()->DeleteSubrange(
+        internal::kOmniboxEventLimit,
+        uma_proto_.omnibox_event_size() - internal::kOmniboxEventLimit);
+  }
+}
+
 void MetricsLog::GetEncodedLog(std::string* encoded_log) {
   DCHECK(closed_);
   uma_proto_.SerializeToString(encoded_log);