Quantify initial stability report edge cases.

base/metrics/histogram_macros.h

Index: base/metrics/histogram_macros.h
diff --git a/base/metrics/histogram_macros.h b/base/metrics/histogram_macros.h
index dcde7255c8dafee8e28c09e21baf492408ea8682..4850e195ebace18901edfdb2ea5fa0c002ae4426 100644
--- a/base/metrics/histogram_macros.h
+++ b/base/metrics/histogram_macros.h
@@ -229,9 +229,24 @@
     name, sample, 1, 10000, 50)
 
 #define UMA_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
-    STATIC_HISTOGRAM_POINTER_BLOCK(name, Add(sample), \
-        base::Histogram::FactoryGet(name, min, max, bucket_count, \
-            base::HistogramBase::kUmaTargetedHistogramFlag))
+  UMA_HISTOGRAM_CUSTOM_COUNTS_WITH_FLAG(                                  \
+      name, sample, min, max, bucket_count,                               \
+      base::HistogramBase::kUmaTargetedHistogramFlag)
+
+#define UMA_STABILITY_HISTOGRAM_COUNTS_100(name, sample) \
+  UMA_STABILITY_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1, 100, 50)
+
+#define UMA_STABILITY_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, \
+                                              bucket_count)           \
+  UMA_HISTOGRAM_CUSTOM_COUNTS_WITH_FLAG(                              \
+      name, sample, min, max, bucket_count,                           \
+      base::HistogramBase::kUmaStabilityHistogramFlag)
+
+#define UMA_HISTOGRAM_CUSTOM_COUNTS_WITH_FLAG(name, sample, min, max, \

[Alexei Svitkine (slow), 2016/09/08 18:41:12]

Nit: Don't use UMA_ prefix here since the kUma flag is not necessarily set.

I would actually name the INTERNAL_HISTOGRAM_CUSTOM_COUNTS_WITH_FLAG to indicate
it's not meant to be used from outside this file. Could you also add the
INTERNAL_ prefix to HISTOGRAM_ENUMERATION_WITH_FLAG macro for consistency?

Finally, can you define this somewhere above - so it's defined before it's used.
(It's not strictly necessary for correct compilation, but I found it weird to
use before it's been declared.)

[manzagop (departed), 2016/09/08 20:54:30]

Done. 

Also rewrote LOCAL_HISTOGRAM_CUSTOM_COUNTS to make use of it.

Tell me if the new location is ok. I've moved it close to
INTERNAL_HISTOGRAM_ENUMERATION_WITH_FLAG. I've put it after
LOCAL_HISTOGRAM_CUSTOM_COUNTS to follow with the trend, since
LOCAL_HISTOGRAM_CUSTOM_COUNTS is defined after eg LOCAL_HISTOGRAM_COUNTS_100
which makes use of it.

+                                              bucket_count, flag)     \
+  STATIC_HISTOGRAM_POINTER_BLOCK(                                     \
+      name, Add(sample),                                              \
+      base::Histogram::FactoryGet(name, min, max, bucket_count, flag))
 
 #define UMA_HISTOGRAM_MEMORY_KB(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1000, 500000, 50)