TabManager: Add more logs to understand how it works when memory is low.

chrome/browser/chromeos/arc/process/arc_process.cc

Index: chrome/browser/chromeos/arc/process/arc_process.cc
diff --git a/chrome/browser/chromeos/arc/process/arc_process.cc b/chrome/browser/chromeos/arc/process/arc_process.cc
index abb054a67c82ae8c9a0208f138eea0935f1e33cc..bd32d481263aed8d6361a86d3571252bd6cf7a18 100644
--- a/chrome/browser/chromeos/arc/process/arc_process.cc
+++ b/chrome/browser/chromeos/arc/process/arc_process.cc
@@ -6,6 +6,8 @@
 
 #include <utility>
 
+#include "base/strings/string_util.h"
+
 namespace arc {
 
 ArcProcess::ArcProcess(base::ProcessId nspid,
@@ -34,4 +36,14 @@ bool ArcProcess::operator<(const ArcProcess& rhs) const {
 ArcProcess::ArcProcess(ArcProcess&& other) = default;
 ArcProcess& ArcProcess::operator=(ArcProcess&& other) = default;
 
+std::ostream& operator<<(std::ostream& out, const ArcProcess& arc_process) {
+  out << "process_name: " << arc_process.process_name()
+      << ", pid: " << arc_process.pid()
+      << ", process_state: " << arc_process.process_state()
+      << ", is_focused: " << arc_process.is_focused()
+      << ", last_activity_time: " << arc_process.last_activity_time()
+      << ", packages: " << base::JoinString(arc_process.packages(), ",");
+  return out;
+}
+
 }  // namespace arc