Add MemoryMonitorAndroid

content/browser/memory/memory_monitor_android.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/memory/memory_monitor_android.h"
+
+#include "base/android/context_utils.h"
+#include "base/android/jni_android.h"
+#include "base/memory/ptr_util.h"
+#include "jni/MemoryMonitorAndroid_jni.h"
+
+namespace content {
+
+namespace {
+const size_t kMBShift = 20;
+}
+
+// static
+std::unique_ptr<MemoryMonitorAndroid> MemoryMonitorAndroid::Create() {
+  return base::WrapUnique(new MemoryMonitorAndroid);
+}
+
+// static
+bool MemoryMonitorAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+MemoryMonitorAndroid::MemoryMonitorAndroid() {}
+
+MemoryMonitorAndroid::~MemoryMonitorAndroid() {}
+
+int MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB() {
+  MemoryInfo info;
+  GetMemoryInfo(&info);
+  return (info.avail_mem - info.threshold) >> kMBShift;
+}
+
+void MemoryMonitorAndroid::GetMemoryInfo(MemoryInfo* out) {
+  DCHECK(out);
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_MemoryMonitorAndroid_getMemoryInfo(
+      env, base::android::GetApplicationContext(),
+      reinterpret_cast<intptr_t>(out));
+}
+
+// Called by JNI to populate ActivityManager.MemoryInfo.
+static void GetMemoryInfoCallback(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jclass>& clazz,
+    jlong avail_mem,
+    jboolean low_memory,
+    jlong threshold,
+    jlong total_mem,
+    jlong out_ptr) {
+  DCHECK(out_ptr);
+  MemoryMonitorAndroid::MemoryInfo* info =
+      reinterpret_cast<MemoryMonitorAndroid::MemoryInfo*>(out_ptr);
+  info->avail_mem = avail_mem;
+  info->low_memory = low_memory;
+  info->threshold = threshold;
+  info->total_mem = total_mem;
+}
+
+// Implementation of a factory function defined in memory_monitor.h.
+std::unique_ptr<MemoryMonitor> CreateMemoryMonitor() {
+  return MemoryMonitorAndroid::Create();
+}
+
+}  // namespace content