memory-infra: Add a struct to carry memory use information

base/trace_event/memory_dump_request_args.h

Index: base/trace_event/memory_dump_request_args.h
diff --git a/base/trace_event/memory_dump_request_args.h b/base/trace_event/memory_dump_request_args.h
index 90a866fa7a3fbd229b0290cf8053f7fa6861127c..c238cdf4f21807e1dbdeb28801586cc06703cb0c 100644
--- a/base/trace_event/memory_dump_request_args.h
+++ b/base/trace_event/memory_dump_request_args.h
@@ -9,10 +9,12 @@
 // These are also used in the IPCs for coordinating inter-process memory dumps.
 
 #include <stdint.h>
+#include <map>
 #include <string>
 
 #include "base/base_export.h"
 #include "base/callback.h"
+#include "base/process/process_handle.h"
 
 namespace base {
 namespace trace_event {
@@ -72,6 +74,31 @@ struct MemoryDumpArgs {
   MemoryDumpLevelOfDetail level_of_detail;
 };
 
+struct MemoryDumpCallbackResult {

[Primiano Tucci (use gerrit), 2017/03/21 15:26:06]

maybe add a comment explaiing what this will be for.
Also add a TODO(hjd) to make it explicit that this is not used yet and will be
used soon.

+  struct OSMemDump {
+    uint32_t pss_kb;
+    uint32_t private_dirty;

[Primiano Tucci (use gerrit), 2017/03/21 15:26:06]

+kb

+  };
+  struct ChromeMemDump {
+    uint32_t malloc_total_kb;
+    uint32_t partition_alloc_total_kb;
+    uint32_t blink_gc_total_kb;
+    uint32_t v8_total_kb;
+  };
+
+  // These are for the current process.
+  OSMemDump os_dump;
+  ChromeMemDump chrome_dump;
+
+  // This is optional and is used only in one case (Linux desktop) by the
+  // browser process, when it needs to communicate the details of the
+  // OSMemDump of other processes.
+  std::map<ProcessId, OSMemDump> os_dump_for_child_processes;

[Primiano Tucci (use gerrit), 2017/03/21 15:26:06]

maybe call this |extra_processes_dump|

base is not really supposed to know about browser/"child" processes (although we
stretched this rule in comments a bit, so it's fine there).
I'd probably make the comment a bit more explicit about the use case thoguh. I'd
say something like:
--
In some cases, os stats can only be dumped from a priviledged process to get
around to sandboxing/selinux restrictions (see crbug.com/461788) 
--

+
+  MemoryDumpCallbackResult();
+  ~MemoryDumpCallbackResult();
+};
+
 using MemoryDumpCallback = Callback<void(uint64_t dump_guid, bool success)>;
 
 BASE_EXPORT const char* MemoryDumpTypeToString(const MemoryDumpType& dump_type);