Add Platform::physicalMemoryInBytes to WebKitPlatformSupportImpl.

webkit/child/webkitplatformsupport_impl.cc

Index: webkit/child/webkitplatformsupport_impl.cc
diff --git a/webkit/child/webkitplatformsupport_impl.cc b/webkit/child/webkitplatformsupport_impl.cc
index 8f68c3a4565c5192dfc3697adb0be1527c5d6e9c..9bdcd25615093e92910244d1f039c018308aae5e 100644
--- a/webkit/child/webkitplatformsupport_impl.cc
+++ b/webkit/child/webkitplatformsupport_impl.cc
@@ -859,6 +859,10 @@ size_t WebKitPlatformSupportImpl::actualMemoryUsageMB() {
   return getMemoryUsageMB(true);
 }
 
+size_t WebKitPlatformSupportImpl::physicalMemoryMB() {
+  return static_cast<size_t>(base::SysInfo::AmountOfPhysicalMemoryMB());
+}
+
 void WebKitPlatformSupportImpl::startHeapProfiling(
   const WebKit::WebString& prefix) {
   // FIXME(morrita): Make this built on windows.