Cleanup histogram classes mixing SetFlags into FactoryGet arguments

Generic cleanup of histogram class, renaming *FactoryGet to FactoryGet,
along with reformatting.

The macros were cleaned up to use common sub-macros rather than
repeating code as much.

Removed ThreadSafeHistogram (and associated ASSET_HISTOGRAM macros)
since this class was not getting used.

I introduced UMA_HISTOGRAM_ENUMERATION to support the common use
of LinearHistograms to count various enumerated values.

I added a Flags argument to all the FactoryGet routines to help avoid 
needing to call SetFlags each time a new sample is Add()ed.  This also
simplifies the code.

This will all help prepare for a "don't histogram at all" macro setting
so that I can test the impact of the histogram macro calls on
performance (since there are now so many active histograms).

BUG=31206
r=raman.tenneti
Review URL: http://codereview.chromium.org/515033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@35295 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 3 insertions, 4 deletions

diff --git a/chrome/browser/net/dns_host_info.cc b/chrome/browser/net/dns_host_info.cc
index 755f54d..8946f7f 100644
--- a/chrome/browser/net/dns_host_info.cc
+++ b/chrome/browser/net/dns_host_info.cc
@@ -104,10 +104,9 @@ void DnsHostInfo::RemoveFromQueue() {
   }
   // Make a custom linear histogram for the region from 0 to boundary.
   const size_t kBucketCount = 52;
-  static scoped_refptr<Histogram> histogram =
-      LinearHistogram::LinearHistogramFactoryGet("DNS.QueueRecycledUnder2",
-          TimeDelta(), kBoundary, kBucketCount);
-  histogram->SetFlags(kUmaTargetedHistogramFlag);
+  static scoped_refptr<Histogram> histogram = LinearHistogram::FactoryGet(
+      "DNS.QueueRecycledUnder2", TimeDelta(), kBoundary, kBucketCount,
+      Histogram::kUmaTargetedHistogramFlag);
   histogram->AddTime(queue_duration_);
 }