Add Web Resources usage to chrome://tracing.

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

Index: third_party/WebKit/Source/core/fetch/MemoryCache.cpp
diff --git a/third_party/WebKit/Source/core/fetch/MemoryCache.cpp b/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
index 9e179a922cc0e68183c4297864aa79eafdd4e9eb..af6d22393dc42baacf4a2b249c66c77beb96f25f 100644
--- a/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
+++ b/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
@@ -105,6 +105,7 @@ inline MemoryCache::MemoryCache()
     , m_statsTimer(this, &MemoryCache::dumpStats)
 #endif
 {
+    Platform::current()->registerMemoryDumpProvider(this);
 #ifdef MEMORY_CACHE_STATS
     const double statsIntervalInSeconds = 15;
     m_statsTimer.startRepeating(statsIntervalInSeconds, FROM_HERE);
@@ -118,6 +119,7 @@ MemoryCache* MemoryCache::create()
 
 MemoryCache::~MemoryCache()
 {
+    Platform::current()->unregisterMemoryDumpProvider(this);
     if (m_prunePending)
         Platform::current()->currentThread()->removeTaskObserver(this);
 }
@@ -780,6 +782,17 @@ void MemoryCache::updateFramePaintTimestamp()
     m_lastFramePaintTimeStamp = currentTime();
 }
 
+bool MemoryCache::onMemoryDump(WebMemoryDumpLevelOfDetail levelOfDetail, WebProcessMemoryDump* memoryDump)
+{
+    for (const auto& resourceMapIter : m_resourceMaps) {
+        for (const auto& resourceIter : *resourceMapIter.value) {
+            Resource* resource = resourceIter.value->m_resource.get();
+            resource->onMemoryDump(memoryDump);
+        }
+    }
+    return true;
+}
+
 void MemoryCache::registerLiveResource(Resource& resource)
 {
 #if ENABLE(OILPAN)