[tracing] Dump child processes' memory metrics in browser

components/tracing/child_memory_dump_manager_delegate_impl.cc

Index: components/tracing/child_memory_dump_manager_delegate_impl.cc
diff --git a/components/tracing/child_memory_dump_manager_delegate_impl.cc b/components/tracing/child_memory_dump_manager_delegate_impl.cc
index fe5c952f6a9a91ecf83ce42e81e49b543eb42974..5cb3a74b2601e9eefd11bca0af708300ba2ce788 100644
--- a/components/tracing/child_memory_dump_manager_delegate_impl.cc
+++ b/components/tracing/child_memory_dump_manager_delegate_impl.cc
@@ -6,6 +6,7 @@
 
 #include "base/single_thread_task_runner.h"

[Primiano Tucci (use gerrit), 2015/11/17 10:44:12]

include what you use: add explicit build_config.h include

[ssid, 2015/11/17 13:55:06]

Done.

 #include "components/tracing/child_trace_message_filter.h"
+#include "components/tracing/process_metrics_memory_dump_manager.h"
 
 namespace tracing {
 
@@ -49,6 +50,12 @@ void ChildMemoryDumpManagerDelegateImpl::SetChildTraceMessageFilter(
   if (ctmf) {
     base::trace_event::MemoryDumpManager::GetInstance()->Initialize(
       this /* delegate */, false /* is_coordinator */);
+
+#if !defined(OS_LINUX)
+    // Do not register in linux due to sandbox.

[Primiano Tucci (use gerrit), 2015/11/17 10:44:12]

Make this more explicit and say: on Linux the browser process takes care of
dumping process stats of child processes. The child themselves are not allowed
to do so due to the BPF sandbox.

[ssid, 2015/11/17 13:55:06]

Done.

+    tracing::ProcessMetricsMemoryDumpManager::GetInstance()->RegisterForProcess(
+        base::kNullProcessHandle);
+#endif
   }
 }