Revert of memory-infra: Finish moving to Mojo (2nd attempt)

services/resource_coordinator/memory/coordinator/coordinator_impl.cc

Index: services/resource_coordinator/memory/coordinator/coordinator_impl.cc
diff --git a/services/resource_coordinator/memory/coordinator/coordinator_impl.cc b/services/resource_coordinator/memory/coordinator/coordinator_impl.cc
index 081db1714915be3a30a15a93d5018628004e483c..5c133f803c472c845b70ba40936c9706365beaa7 100644
--- a/services/resource_coordinator/memory/coordinator/coordinator_impl.cc
+++ b/services/resource_coordinator/memory/coordinator/coordinator_impl.cc
@@ -4,41 +4,40 @@
 
 #include "services/resource_coordinator/memory/coordinator/coordinator_impl.h"
 
-#include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
-#include "base/threading/platform_thread.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/memory_dump_request_args.h"
-#include "services/resource_coordinator/public/cpp/memory/memory_dump_manager_delegate_impl.h"
 #include "services/resource_coordinator/public/interfaces/memory/memory_instrumentation.mojom.h"
 
 namespace memory_instrumentation {
 
+namespace {
+
+base::LazyInstance<CoordinatorImpl>::Leaky g_coordinator =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
 // static
 CoordinatorImpl* CoordinatorImpl::GetInstance() {
-  static CoordinatorImpl* instance = new CoordinatorImpl(true);
-  DCHECK(instance->initialize_memory_dump_manager());
-  return instance;
+  return g_coordinator.Pointer();
 }
 
-CoordinatorImpl::CoordinatorImpl(bool initialize_memory_dump_manager)
-    : failed_memory_dump_count_(0),
-      initialize_memory_dump_manager_(initialize_memory_dump_manager) {
-  if (initialize_memory_dump_manager) {
-    MemoryDumpManagerDelegateImpl::Config config(this);
-    MemoryDumpManagerDelegateImpl::Create(config);
-  }
-}
+// TODO(chiniforooshan): Initialize the global MemoryDumpManager instance here.
+// This is how the global MemoryDumpManager gets a reference to the delegate on
+// the service (read the browser) process for service process memory dumps. This
+// can be done when the delegate implementation is landed.
+CoordinatorImpl::CoordinatorImpl() : failed_memory_dump_count_(0) {}
 
 CoordinatorImpl::~CoordinatorImpl() {}
 
 void CoordinatorImpl::BindCoordinatorRequest(
     mojom::CoordinatorRequest request) {
-  DCHECK(thread_checker_.CalledOnValidThread());
   bindings_.AddBinding(this, std::move(request));
 }
 
@@ -53,6 +52,7 @@
     const base::trace_event::MemoryDumpRequestArgs& args,
     const RequestGlobalMemoryDumpCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
+
   bool another_dump_already_in_progress = !queued_memory_dump_requests_.empty();
 
   // If this is a periodic memory dump request and there already is another
@@ -88,6 +88,7 @@
 void CoordinatorImpl::RegisterProcessLocalDumpManager(
     mojom::ProcessLocalDumpManagerPtr process_manager) {
   DCHECK(thread_checker_.CalledOnValidThread());
+
   process_manager.set_connection_error_handler(
       base::Bind(&CoordinatorImpl::UnregisterProcessLocalDumpManager,
                  base::Unretained(this), process_manager.get()));
@@ -100,8 +101,7 @@
 
 void CoordinatorImpl::UnregisterProcessLocalDumpManager(
     mojom::ProcessLocalDumpManager* process_manager) {
-  size_t num_deleted = process_managers_.erase(process_manager);
-  DCHECK(num_deleted == 1);
+  DCHECK(process_managers_.erase(process_manager) == 1);
 
   // Check if we are waiting for an ack from this process-local manager.
   if (pending_process_managers_.find(process_manager) !=