Put histogram code in disk_cache on a diet.

net/disk_cache/blockfile/histogram_macros_v3.h

Index: net/disk_cache/blockfile/histogram_macros_v3.h
diff --git a/net/disk_cache/blockfile/histogram_macros_v3.h b/net/disk_cache/blockfile/histogram_macros_v3.h
index e992a7c3f6950d6d8dfb82dfc39b2fa97e3371b3..e6fdef3c0eda9f08982596fe5f9a259aa7b1a514 100644
--- a/net/disk_cache/blockfile/histogram_macros_v3.h
+++ b/net/disk_cache/blockfile/histogram_macros_v3.h
@@ -16,12 +16,10 @@
 // These histograms follow the definition of UMA_HISTOGRAMN_XXX except that
 // whenever the name changes (the experiment group changes), the histrogram
 // object is re-created.
-// Note: These macros are only run on one thread, so the declarations of
-// |counter| was made static (i.e., there will be no race for reinitialization).
 
 #define CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
     do { \
-      static base::HistogramBase* counter(NULL); \
+      base::HistogramBase* counter(NULL); \
       if (!counter || name != counter->histogram_name()) \
         counter = base::Histogram::FactoryGet( \
             name, min, max, bucket_count, \
@@ -40,7 +38,7 @@
 
 #define CACHE_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
     do { \
-      static base::HistogramBase* counter(NULL); \
+      base::HistogramBase* counter(NULL); \
       if (!counter || name != counter->histogram_name()) \
         counter = base::Histogram::FactoryTimeGet( \
             name, min, max, bucket_count, \
@@ -53,7 +51,7 @@
     base::TimeDelta::FromSeconds(10), 50)
 
 #define CACHE_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
-    static base::HistogramBase* counter(NULL); \
+    base::HistogramBase* counter(NULL); \
     if (!counter || name != counter->histogram_name()) \
       counter = base::LinearHistogram::FactoryGet( \
                     name, 1, boundary_value, boundary_value + 1, \
@@ -96,23 +94,16 @@
     const std::string my_name =\
         CACHE_UMA_BACKEND_IMPL_OBJ->HistogramName(name);\
     switch (CACHE_UMA_BACKEND_IMPL_OBJ->cache_type()) {\
+      default:\
+        NOTREACHED();\

[rvargas (doing something else), 2014/03/17 19:41:00]

Don't add a NOTREACHED here... I'm going with no histograms by default :)

+        /* Fall-through. */\
       case net::DISK_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::MEDIA_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::APP_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::SHADER_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::PNACL_CACHE:\
         CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
-      default:\
-        break;\
     }\
   }