Add current rss and embedder name to Observatory

runtime/bin/process_android.cc

Index: runtime/bin/process_android.cc
diff --git a/runtime/bin/process_android.cc b/runtime/bin/process_android.cc
index 66fc280523091c99fa593a120e872a8b9738e42e..ee9fb0ccda9f96072ff65dd3e2c05f78fd29c3d8 100644
--- a/runtime/bin/process_android.cc
+++ b/runtime/bin/process_android.cc
@@ -861,20 +861,16 @@ intptr_t Process::CurrentProcessId() {
 
 int64_t Process::CurrentRSS() {
   // The second value in /proc/self/statm is the current RSS in pages.
-  File* statm = File::Open("/proc/self/statm", File::kRead);
+  // It is not possible to use getrusage() because the interested fields are not
+  // implemented by the linux kernel.
+  FILE* statm = fopen("/proc/self/statm", "r");
   if (statm == NULL) {
     return -1;
   }
-  RefCntReleaseScope<File> releaser(statm);
-  const intptr_t statm_length = 1 * KB;
-  void* buffer = reinterpret_cast<void*>(Dart_ScopeAllocate(statm_length));
-  const intptr_t statm_read = statm->Read(buffer, statm_length);
-  if (statm_read <= 0) {
-    return -1;
-  }
   int64_t current_rss_pages = 0;
-  int matches = sscanf(reinterpret_cast<char*>(buffer), "%*s%" Pd64 "",
+  int matches = fscanf(statm, "%*s%" Pd64 "",
                        &current_rss_pages);

[zra, 2017/08/10 22:19:50]

It looks like this will fit on the line above.

[cbernaschina, 2017/08/12 00:29:42]

Done.

+  fclose(statm);

[zra, 2017/08/10 22:19:50]

This will blow away errno from fscanf when there is an error.

[cbernaschina, 2017/08/10 22:40:28]

If matches is 1 it means that the value was successfully red. Should we check
even  ferror? Or do we need to preserve errno for other reasons?

[zra, 2017/08/10 22:49:47]

If this function returns -1, the caller will make a new Dart OSError object
whose fields are populated by looking at errno.

[cbernaschina, 2017/08/12 00:29:42]

Done.

   if (matches != 1) {
     return -1;
   }