Adjust max number of samples that can be stored for a histogram (2000->300).

webrtc/system_wrappers/source/metrics_default.cc

Index: webrtc/system_wrappers/source/metrics_default.cc
diff --git a/webrtc/system_wrappers/source/metrics_default.cc b/webrtc/system_wrappers/source/metrics_default.cc
index 34d33a2179cf669a204a16d2176b4899a626e698..49004543ea177938a7cd49a6ab6a784f5af26ee8 100644
--- a/webrtc/system_wrappers/source/metrics_default.cc
+++ b/webrtc/system_wrappers/source/metrics_default.cc
@@ -24,7 +24,7 @@ namespace {
 // Limit for the maximum number of sample values that can be stored.
 // TODO(asapersson): Consider using bucket count (and set up
 // linearly/exponentially spaced buckets) if samples are logged more frequently.
-const int kMaxSampleMapSize = 2000;
+const int kMaxSampleMapSize = 300;
 
 class RtcHistogram {
  public: