Add UMA to track time between preload discovery and reference

third_party/WebKit/Source/core/fetch/FetchRequest.cpp

Index: third_party/WebKit/Source/core/fetch/FetchRequest.cpp
diff --git a/third_party/WebKit/Source/core/fetch/FetchRequest.cpp b/third_party/WebKit/Source/core/fetch/FetchRequest.cpp
index 7fe6ab527e118d8693f95b878173e8e8bbe4f019..b26a62d25e27d74de620cd25157d51601c3a9f2a 100644
--- a/third_party/WebKit/Source/core/fetch/FetchRequest.cpp
+++ b/third_party/WebKit/Source/core/fetch/FetchRequest.cpp
@@ -37,6 +37,7 @@ FetchRequest::FetchRequest(const ResourceRequest& resourceRequest, const AtomicS
     , m_priority(priority)
     , m_forPreload(false)
     , m_linkPreload(false)
+    , m_preloadDiscoveryTime(0.0)
     , m_defer(NoDefer)
     , m_originRestriction(UseDefaultOriginRestrictionForType)
 {
@@ -49,6 +50,7 @@ FetchRequest::FetchRequest(const ResourceRequest& resourceRequest, const AtomicS
     , m_priority(ResourceLoadPriorityUnresolved)
     , m_forPreload(false)
     , m_linkPreload(false)
+    , m_preloadDiscoveryTime(0.0)
     , m_defer(NoDefer)
     , m_originRestriction(UseDefaultOriginRestrictionForType)
 {
@@ -61,6 +63,7 @@ FetchRequest::FetchRequest(const ResourceRequest& resourceRequest, const FetchIn
     , m_priority(ResourceLoadPriorityUnresolved)
     , m_forPreload(false)
     , m_linkPreload(false)
+    , m_preloadDiscoveryTime(0.0)
     , m_defer(NoDefer)
     , m_originRestriction(UseDefaultOriginRestrictionForType)
 {
@@ -98,4 +101,10 @@ void FetchRequest::setResourceWidth(ResourceWidth resourceWidth)
     }
 }
 
+void FetchRequest::setForPreload(bool forPreload, double discoveryTime)
+{
+    m_forPreload = forPreload;
+    m_preloadDiscoveryTime = discoveryTime;
+}
+
 } // namespace blink