media: Use UmaHistogramEnumeration() where applicable

Prefer UmaHistogram* function to using the histogram directly.

Change-Id: I9eb38bf856c76fe50ff094a7728ef1f7aebe239a
Reviewed-on: https://chromium-review.googlesource.com/804697Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521501}

media/blink/cdm_result_promise_helper.cc

@@ -5,7 +5,7 @@
 #include "media/blink/cdm_result_promise_helper.h"
 
 #include "base/logging.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_functions.h"
 
 namespace media {
 
@@ -69,12 +69,7 @@ void ReportCdmResultUMA(const std::string& uma_name, CdmResultForUMA result) {
   if (uma_name.empty())
     return;
 
-  base::LinearHistogram::FactoryGet(
-      uma_name,
-      1,
-      NUM_RESULT_CODES,
-      NUM_RESULT_CODES + 1,
-      base::HistogramBase::kUmaTargetedHistogramFlag)->Add(result);
+  base::UmaHistogramEnumeration(uma_name, result, NUM_RESULT_CODES);
 }
 
 }  // namespace media

media/blink/webencryptedmediaclient_impl.cc

@@ -8,7 +8,7 @@
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "media/base/key_systems.h"
@@ -72,12 +72,8 @@ class WebEncryptedMediaClientImpl::Reporter {
 
  private:
   void Report(KeySystemSupportStatus status) {
-    // Not using UMA_HISTOGRAM_ENUMERATION directly because UMA_* macros
-    // require the names to be constant throughout the process' lifetime.
-    base::LinearHistogram::FactoryGet(
-        uma_name_, 1, KEY_SYSTEM_SUPPORT_STATUS_COUNT,
-        KEY_SYSTEM_SUPPORT_STATUS_COUNT + 1,
-        base::Histogram::kUmaTargetedHistogramFlag)->Add(status);
+    base::UmaHistogramEnumeration(uma_name_, status,
+                                  KEY_SYSTEM_SUPPORT_STATUS_COUNT);
   }
 
   const std::string uma_name_;