Add a test for MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB

content/browser/memory/memory_monitor_android.h

 // 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.
 
 #ifndef CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_ANDROID_H_
 #define CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_ANDROID_H_
 
 #include <jni.h>
 
 #include "content/browser/memory/memory_monitor.h"
 
 namespace content {
 
 // A memory monitor for the Android system.
 class CONTENT_EXPORT MemoryMonitorAndroid : public MemoryMonitor {
  public:
   static std::unique_ptr<MemoryMonitorAndroid> Create();
 
   static bool Register(JNIEnv* env);
 
   // C++ counter-part of ActivityManager.MemoryInfo
   struct MemoryInfo {
     jlong avail_mem;
     jboolean low_memory;
     jlong threshold;
     jlong total_mem;
   };
 
+  // Delegate interface used by MemoryMonitorAndroid.
+  class Delegate {
+   public:
+    Delegate() {}
+    virtual ~Delegate() {};
+
+    // Get MemoryInfo. Implementations should fill |out| accordingly.
+    virtual void GetMemoryInfo(MemoryInfo* out) = 0;
+  };
+
+  MemoryMonitorAndroid(std::unique_ptr<Delegate> delegate);
   ~MemoryMonitorAndroid() override;
 
   // MemoryMonitor implementation:
   int GetFreeMemoryUntilCriticalMB() override;
 
   // Get memory info from the Android system.
   void GetMemoryInfo(MemoryInfo* out);
 
+  Delegate* delegate() { return delegate_.get(); }
+
  private:
-  MemoryMonitorAndroid();
+  std::unique_ptr<Delegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryMonitorAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEMORY_MEMORY_MONITOR_ANDROID_H_