Add Web Resources usage to chrome://tracing.

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

Index: third_party/WebKit/Source/core/fetch/Resource.cpp
diff --git a/third_party/WebKit/Source/core/fetch/Resource.cpp b/third_party/WebKit/Source/core/fetch/Resource.cpp
index f1aaf35ded75c5e9d21ed0548344ec9bd3c24798..b6417f2b8e2b310d800b928052340fc7205a7091 100644
--- a/third_party/WebKit/Source/core/fetch/Resource.cpp
+++ b/third_party/WebKit/Source/core/fetch/Resource.cpp
@@ -39,6 +39,7 @@
 #include "platform/TraceEvent.h"
 #include "platform/weborigin/KURL.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebProcessMemoryDump.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/MathExtras.h"
 #include "wtf/StdLibExtras.h"
@@ -717,6 +718,37 @@ void Resource::prune()
     unlock();
 }
 
+void Resource::onMemoryDump(WebProcessMemoryDump* memoryDump) const
+{
+    const String dumpName = getMemoryDumpName();
+    WebMemoryAllocatorDump* dump = memoryDump->createMemoryAllocatorDump(dumpName);
+    dump->AddScalar("encoded_size", "bytes", m_encodedSize);
+    dump->AddScalar("decoded_size", "bytes", m_decodedSize);
+    if (hasClients()) {

[haraken, 2015/09/28 14:54:02]

This condition is not quite right. Even if the Resource doesn't have a client,
it doesn't always mean that it is dead. Actually, the live/dead condition of
Resources is extremely complicated (See the implementation of
Resource::canDelete()).

You should make the condition more correct. You can refer to the implementation
of MemoryCache::pruneLiveResources and MemoryCache::pruneDeadResources, which
handle the liveness/deadness correctly.

[ssid, 2015/09/28 16:24:38]

Yes I had checked the MemoryCache::pruneDeadResources. But I also found the
MemoryCache::getStatistics, which takes the resource as live if it has clients.
This sounded more appropriate. It is more like I don't get the definition of
"live"

I am not convinced with the conditions like:
1. !m_loader (resource is loading but need not be live)
2. !m_preloadCount - resource is preloaded but no one is using it yet.
3. !m_proxyResource - If there is a proxy updating the resource, why should it
be called live, when there are no clients using it.

Now changed since the other cases seem imply it is live.

+        dump->AddScalar("live_size", "bytes", m_encodedSize);
+    } else {
+        dump->AddScalar("dead_size", "bytes", m_encodedSize);
+    }
+
+    size_t totalSize = encodedSize() + overheadSize();
+    dump->AddScalar("purged_size", "bytes", wasPurged() ? totalSize : 0);
+    if (m_data) {
+        const bool purgeable = m_data->isLocked() && !wasPurged();

[haraken, 2015/09/28 14:54:02]

Can't we just use isPurgeable()?

[ssid, 2015/09/28 16:24:38]

Sorry didn't know this existed. There are so many methods to read through.
Thanks fixed.

+        dump->AddScalar("purgeable_size", "bytes", purgeable ? 0 : totalSize);
+        m_data->onMemoryDump(dumpName, memoryDump);
+    }
+
+    const String overheadName = dumpName + "/overhead";
+    WebMemoryAllocatorDump* overheadDump = memoryDump->createMemoryAllocatorDump(overheadName);
+    overheadDump->AddScalar("size", "bytes", overheadSize());
+    memoryDump->AddSuballocation(overheadDump->guid(), String(WTF::Partitions::allocatorPoolNameForTracing()));
+}
+
+String Resource::getMemoryDumpName() const
+{
+    return String::format("web_cache/%s_resources/%ld", resourceTypeToString(type(), options().initiatorInfo), m_identifier);
+}
+
 void Resource::setResourceToRevalidate(Resource* resource)
 {
     ASSERT(resource);