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

components/web_cache/renderer/web_cache_render_process_observer.cc

Index: components/web_cache/renderer/web_cache_render_process_observer.cc
diff --git a/components/web_cache/renderer/web_cache_render_process_observer.cc b/components/web_cache/renderer/web_cache_render_process_observer.cc
index a273817a2c0d957d798930a0a6ad65ddfa1947f1..3250624766cd0a6003afe1c0e81b817de9cb2321 100644
--- a/components/web_cache/renderer/web_cache_render_process_observer.cc
+++ b/components/web_cache/renderer/web_cache_render_process_observer.cc
@@ -6,7 +6,10 @@
 
 #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;
@@ -53,10 +56,16 @@ void WebCacheRenderProcessObserver::WebKitInitialized() {
                             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(