[tracing] Support BACKGROUND mode in MemoryCache dump provider

third_party/WebKit/Source/platform/MemoryCacheDumpProvider.cpp

 // Copyright 2015 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 "platform/MemoryCacheDumpProvider.h"
 
 namespace blink {
 
 DEFINE_TRACE(MemoryCacheDumpClient)
 {
 }
 
 MemoryCacheDumpProvider* MemoryCacheDumpProvider::instance()
 {
     DEFINE_STATIC_LOCAL(MemoryCacheDumpProvider, instance, ());
     return &instance;
 }
 
 bool MemoryCacheDumpProvider::OnMemoryDump(const base::trace_event::MemoryDumpArgs& args, base::trace_event::ProcessMemoryDump* memoryDump)
 {
     DCHECK(isMainThread());
     if (!m_client)
         return false;
 
     WebMemoryDumpLevelOfDetail level;
     switch (args.level_of_detail) {
+    case base::trace_event::MemoryDumpLevelOfDetail::BACKGROUND:
+        level = blink::WebMemoryDumpLevelOfDetail::Background;
+        break;
     case base::trace_event::MemoryDumpLevelOfDetail::LIGHT:
         level = blink::WebMemoryDumpLevelOfDetail::Light;
         break;
     case base::trace_event::MemoryDumpLevelOfDetail::DETAILED:
         level = blink::WebMemoryDumpLevelOfDetail::Detailed;
         break;
     default:
         NOTREACHED();
         return false;
     }
 
     WebProcessMemoryDump dump(args.level_of_detail, memoryDump);
     return m_client->onMemoryDump(level, &dump);
 }
 
 MemoryCacheDumpProvider::MemoryCacheDumpProvider()
 {
 }
 
 MemoryCacheDumpProvider::~MemoryCacheDumpProvider()
 {
 }
 
 } // namespace blink