Refactor ARC OOM handler code

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..6bafc72ab5c86986ceb9b7374387730ceff75001 100644
--- a/chrome/browser/chromeos/arc/process/arc_process.cc
+++ b/chrome/browser/chromeos/arc/process/arc_process.cc
@@ -8,6 +8,15 @@
 
 namespace arc {
 
+namespace {
+
+// A special process on Android side which serves as a dummy "focused" app
+// when the focused window is a Chrome side window (i.e., all Android
+// processes are running in the background). We don't want to kill it anyway.
+constexpr char kArcHomeProcess[] = "org.chromium.arc.home";
+
+}  // namespace
+
 ArcProcess::ArcProcess(base::ProcessId nspid,
                        base::ProcessId pid,
                        const std::string& process_name,
@@ -34,4 +43,17 @@ bool ArcProcess::operator<(const ArcProcess& rhs) const {
 ArcProcess::ArcProcess(ArcProcess&& other) = default;
 ArcProcess& ArcProcess::operator=(ArcProcess&& other) = default;
 
+bool ArcProcess::IsImportant() const {
+  return process_state() <= mojom::ProcessState::IMPORTANT_FOREGROUND ||
+         process_name() == kArcHomeProcess;

[cylee1, 2017/05/11 19:29:14]

BTW, Is it possible to make the process persistent in AndroidManifest.xml ? I
don't know the xml thing when writing this. 

[Yusuke Sato, 2017/05/11 20:01:30]

Yes, if we want to. I'll work on it in a separate CL.

+}
+
+bool ArcProcess::IsKernelKillable() const {
+  // Protect PERSISTENT, PERSISTENT_UI, and our HOME processes since they should
+  // never be killed even by the kernel. Returning false for them allows their
+  // OOM adjustment scores to remain negative.
+  return process_state() > arc::mojom::ProcessState::PERSISTENT_UI &&
+         process_name() != kArcHomeProcess;
+}
+
 }  // namespace arc