Add a ProcessManager class to store Process objects.

Trying out a new method for exposing global objects directly via a
variable.

zion/scheduler/process_manager.cpp

@@ -0,0 +1,34 @@
+#include "scheduler/process_manager.h"
+
+ProcessManager* gProcMan = nullptr;
+
+void ProcessManager::Init() {
+  gProcMan = new ProcessManager();
+  gProcMan->InsertProcess(Process::RootProcess());
+}
+
+void ProcessManager::InsertProcess(const SharedPtr<Process>& proc) {
+  proc_list_.PushBack(proc);
+}
+
+Process& ProcessManager::FromId(uint64_t pid) {
+  auto iter = proc_list_.begin();
+  while (iter != proc_list_.end()) {
+    if (iter->id() == pid) {
+      return **iter;
+    }
+    ++iter;
+  }
+
+  panic("Searching for invalid process id");
+  return *((Process*)0);
+}
+
+void ProcessManager::DumpProcessStates() {
+  dbgln("Process States: %u", proc_list_.size());
+  auto iter = proc_list_.begin();
+  while (iter != proc_list_.end()) {
+    dbgln("%u: %u", iter->id(), iter->GetState());
+    ++iter;
+  }
+}