FBTF: Move virtual methods to implementation files.

Remove logging.h and other headers where possible.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/3461019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60369 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/metrics/metrics_log.cc b/chrome/browser/metrics/metrics_log.cc
index 396c5335..7d602e6e 100644
--- a/chrome/browser/metrics/metrics_log.cc
+++ b/chrome/browser/metrics/metrics_log.cc
@@ -83,6 +83,10 @@
   return version;
 }
 
+MetricsLog* MetricsLog::AsMetricsLog() {
+  return this;
+}
+
 void MetricsLog::RecordIncrementalStabilityElements() {
   DCHECK(!locked_);