media: Add UMA to record time to GenerateRequest and LoadSession

media/blink/new_session_cdm_result_promise.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/blink/new_session_cdm_result_promise.h"
 
 #include "base/logging.h"
+#include "base/metrics/histogram_functions.h"
 #include "media/blink/cdm_result_promise_helper.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace media {
 
+const char kTimeUMAPrefix[] = "TimeTo.";
+
 static blink::WebContentDecryptionModuleResult::SessionStatus ConvertStatus(
     SessionInitStatus status) {
   switch (status) {
     case SessionInitStatus::UNKNOWN_STATUS:
       break;
     case SessionInitStatus::NEW_SESSION:
       return blink::WebContentDecryptionModuleResult::NewSession;
     case SessionInitStatus::SESSION_NOT_FOUND:
       return blink::WebContentDecryptionModuleResult::SessionNotFound;
     case SessionInitStatus::SESSION_ALREADY_EXISTS:
       return blink::WebContentDecryptionModuleResult::SessionAlreadyExists;
   }
   NOTREACHED();
   return blink::WebContentDecryptionModuleResult::SessionNotFound;
 }
 
 NewSessionCdmResultPromise::NewSessionCdmResultPromise(
     const blink::WebContentDecryptionModuleResult& result,
+    const std::string& key_system_uma_prefix,
     const std::string& uma_name,
     const SessionInitializedCB& new_session_created_cb)
     : web_cdm_result_(result),
+      key_system_uma_prefix_(key_system_uma_prefix),
       uma_name_(uma_name),
-      new_session_created_cb_(new_session_created_cb) {
-}
+      new_session_created_cb_(new_session_created_cb),
+      creation_time_(base::TimeTicks::Now()) {}
 
 NewSessionCdmResultPromise::~NewSessionCdmResultPromise() {
   if (!IsPromiseSettled())
     RejectPromiseOnDestruction();
 }
 
 void NewSessionCdmResultPromise::resolve(const std::string& session_id) {
   // |new_session_created_cb_| uses a WeakPtr<> and may not do anything
   // if the session object has been destroyed.
   SessionInitStatus status = SessionInitStatus::UNKNOWN_STATUS;
   new_session_created_cb_.Run(session_id, &status);
 
   if (status == SessionInitStatus::UNKNOWN_STATUS) {
     reject(INVALID_STATE_ERROR, 0, "Cannot finish session initialization");
     return;
   }
 
   MarkPromiseSettled();
-  ReportCdmResultUMA(uma_name_, SUCCESS);
+  ReportCdmResultUMA(key_system_uma_prefix_ + uma_name_, SUCCESS);
+
+  // Only report time for promise resolution (not rejection).
+  base::UmaHistogramTimes(key_system_uma_prefix_ + kTimeUMAPrefix + uma_name_,
+                          base::TimeTicks::Now() - creation_time_);
+
   web_cdm_result_.completeWithSession(ConvertStatus(status));
 }
 
 void NewSessionCdmResultPromise::reject(CdmPromise::Exception exception_code,
                                         uint32_t system_code,
                                         const std::string& error_message) {
   MarkPromiseSettled();
   ReportCdmResultUMA(uma_name_,
                      ConvertCdmExceptionToResultForUMA(exception_code));
   web_cdm_result_.completeWithError(ConvertCdmException(exception_code),
                                     system_code,
                                     blink::WebString::fromUTF8(error_message));
 }
 
 }  // namespace media