Add a test for MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB

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);
-}
+// An implementation of MemoryMonitorAndroid::Delegate using the Android APIs.
+class MemoryMonitorAndroidDelegateImpl : public MemoryMonitorAndroid::Delegate {
+ public:
+  MemoryMonitorAndroidDelegateImpl() {}
+  ~MemoryMonitorAndroidDelegateImpl() override {}
 
-// static
-bool MemoryMonitorAndroid::Register(JNIEnv* env) {
-  return RegisterNativesImpl(env);
-}
+  using MemoryInfo = MemoryMonitorAndroid::MemoryInfo;
+  void GetMemoryInfo(MemoryInfo* out) override;
 
-MemoryMonitorAndroid::MemoryMonitorAndroid() {}
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MemoryMonitorAndroidDelegateImpl);
+};
 
-MemoryMonitorAndroid::~MemoryMonitorAndroid() {}
-
-int MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB() {
-  MemoryInfo info;
-  GetMemoryInfo(&info);
-  return (info.avail_mem - info.threshold) >> kMBShift;
-}
-
-void MemoryMonitorAndroid::GetMemoryInfo(MemoryInfo* out) {
+void MemoryMonitorAndroidDelegateImpl::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;
 }
 
+// static
+std::unique_ptr<MemoryMonitorAndroid> MemoryMonitorAndroid::Create() {
+  auto delegate = base::WrapUnique(new MemoryMonitorAndroidDelegateImpl);
+  return base::WrapUnique(new MemoryMonitorAndroid(std::move(delegate)));
+}
+
+// static
+bool MemoryMonitorAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+MemoryMonitorAndroid::MemoryMonitorAndroid(std::unique_ptr<Delegate> delegate)
+    : delegate_(std::move(delegate)) {
+  DCHECK(delegate_.get());
+}
+
+MemoryMonitorAndroid::~MemoryMonitorAndroid() {}
+
+int MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB() {
+  MemoryInfo info;
+  GetMemoryInfo(&info);
+  return (info.avail_mem - info.threshold) >> kMBShift;
+}
+
+void MemoryMonitorAndroid::GetMemoryInfo(MemoryInfo* out) {
+  delegate_->GetMemoryInfo(out);
+}
+
 // Implementation of a factory function defined in memory_monitor.h.
 std::unique_ptr<MemoryMonitor> CreateMemoryMonitor() {
   return MemoryMonitorAndroid::Create();
 }
 
 }  // namespace content