Reland of [tracing] Dump child processes' memory metrics in browser

components/tracing/BUILD.gn

Index: components/tracing/BUILD.gn
diff --git a/components/tracing/BUILD.gn b/components/tracing/BUILD.gn
index 0111de9b025f18db15d77291fbae606b8e285a1a..927aeb67894b1e398c5a2f96a463126df2fd9a95 100644
--- a/components/tracing/BUILD.gn
+++ b/components/tracing/BUILD.gn
@@ -10,6 +10,8 @@
     "child_trace_message_filter.h",
     "graphics_memory_dump_provider_android.cc",
     "graphics_memory_dump_provider_android.h",
+    "process_metrics_memory_dump_provider.cc",
+    "process_metrics_memory_dump_provider.h",
     "tracing_export.h",
     "tracing_messages.cc",
     "tracing_messages.h",
@@ -21,6 +23,10 @@
     "//base",
     "//ipc",
   ]
+
+  if (is_nacl) {
+    sources -= [ "process_metrics_memory_dump_provider.cc" ]
+  }
 }
 
 component("startup_tracing") {
@@ -46,6 +52,7 @@
 
   sources = [
     "graphics_memory_dump_provider_android_unittest.cc",
+    "process_metrics_memory_dump_provider_unittest.cc",
   ]
 
   deps = [