[tracing] Add browser-side test for memory dumps.

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index ed965fa2b312a8ccc40a0fcd95be2acc485fa8ed..58dfb4be9172b9f8e09edab1e013be2fb3ab1b23 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -111,6 +111,8 @@ void MemoryDumpManager::UnregisterDumpProvider(MemoryDumpProvider* mdp) {
 void MemoryDumpManager::RequestGlobalDump(
     MemoryDumpType dump_type,
     const MemoryDumpCallback& callback) {
+  LOG(ERROR) << "MDM request enabled="
+             << subtle::NoBarrier_Load(&memory_tracing_enabled_);
   // Bail out immediately if tracing is not enabled at all.
   if (!UNLIKELY(subtle::NoBarrier_Load(&memory_tracing_enabled_)))
     return;
@@ -127,6 +129,7 @@ void MemoryDumpManager::RequestGlobalDump(
     delegate = delegate_;
   }
 
+  LOG(ERROR) << "MDM request " << guid << " delegate : " << (void*)delegate;
   if (delegate) {
     // The delegate is in charge to coordinate the request among all the
     // processes and call the CreateLocalDumpPoint on the local process.
@@ -144,6 +147,7 @@ void MemoryDumpManager::RequestGlobalDump(MemoryDumpType dump_type) {
 // Creates a memory dump for the current process and appends it to the trace.
 void MemoryDumpManager::CreateProcessDump(
     const MemoryDumpRequestArgs& args) {
+  LOG(ERROR) << "MDM create " << args.dump_guid;
   bool did_any_provider_dump = false;
   scoped_ptr<ProcessMemoryDump> pmd(new ProcessMemoryDump());
 
@@ -193,6 +197,7 @@ void MemoryDumpManager::OnTraceLogEnabled() {
   TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &enabled);
 
   AutoLock lock(lock_);
+  LOG(ERROR) << "OnTraceLogEnabled " << enabled;
   if (enabled) {
     dump_providers_enabled_.assign(dump_providers_registered_.begin(),
                                    dump_providers_registered_.end());
@@ -203,6 +208,7 @@ void MemoryDumpManager::OnTraceLogEnabled() {
 }
 
 void MemoryDumpManager::OnTraceLogDisabled() {
+  LOG(ERROR) << "OnTraceLogDisabled";
   AutoLock lock(lock_);
   dump_providers_enabled_.clear();
   subtle::NoBarrier_Store(&memory_tracing_enabled_, 0);