[tracing] Add WebCache memory usage in Blink to chrome://tracing

components/web_cache/renderer/web_cache_render_process_observer.cc

 // Copyright 2014 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 "components/web_cache/renderer/web_cache_render_process_observer.h"
 
 #include <limits>
 
+#include "base/thread_task_runner_handle.h"
+#include "base/trace_event/memory_dump_manager.h"
 #include "components/web_cache/common/web_cache_messages.h"
+#include "components/web_cache/renderer/web_cache_memory_dump_provider.h"
 #include "third_party/WebKit/public/web/WebCache.h"
 
 using blink::WebCache;
 
 namespace web_cache {
 
 namespace {
 const size_t kUnitializedCacheCapacity = UINT_MAX;
 }
 
@@ skipping 26 matching lines @@
   return handled;
 }
 
 void WebCacheRenderProcessObserver::WebKitInitialized() {
   webkit_initialized_ = true;
   if (pending_cache_capacity_ != kUnitializedCacheCapacity) {
     WebCache::setCapacities(pending_cache_min_dead_capacity_,
                             pending_cache_max_dead_capacity_,
                             pending_cache_capacity_);
   }
+
+  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
+      web_cache::WebCacheMemoryDumpProvider::GetInstance(),
+      base::ThreadTaskRunnerHandle::Get());
 }
 
 void WebCacheRenderProcessObserver::OnRenderProcessShutdown() {
   webkit_initialized_ = false;

[Primiano Tucci (use gerrit), 2015/08/13 13:30:21]

Just for consistency, I'd make the register and unregister sequence symmetric.
In other words, I'd move the webkit_initialized = false below

[ssid, 2015/08/13 15:25:34]

Done.

+  base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
+      web_cache::WebCacheMemoryDumpProvider::GetInstance());
 }
 
 void WebCacheRenderProcessObserver::OnSetCacheCapacities(
     size_t min_dead_capacity,
     size_t max_dead_capacity,
     size_t capacity) {
   if (!webkit_initialized_) {
     pending_cache_min_dead_capacity_ = min_dead_capacity;
     pending_cache_max_dead_capacity_ = max_dead_capacity;
     pending_cache_capacity_ = capacity;
     return;
   }
 
   WebCache::setCapacities(
       min_dead_capacity, max_dead_capacity, capacity);
 }
 
 void WebCacheRenderProcessObserver::OnClearCache(bool on_navigation) {
   if (on_navigation || !webkit_initialized_)
     clear_cache_pending_ = true;
   else
     WebCache::clear();
 }
 
 }  // namespace web_cache