Introduce moderate binding

content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java

Index: content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java
index e134d3625d3ab16879dfe1c59ed732eb93b97a4f..8170a70bc3c757b7599f7856764755007cbb5132 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ChildProcessConnectionImpl.java
@@ -12,9 +12,9 @@ import android.os.Bundle;
 import android.os.DeadObjectException;
 import android.os.IBinder;
 import android.os.RemoteException;
-import android.util.Log;
 
 import org.chromium.base.CpuFeatures;
+import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.TraceEvent;
 import org.chromium.base.VisibleForTesting;
@@ -63,13 +63,17 @@ public class ChildProcessConnectionImpl implements ChildProcessConnection {
     private ChildServiceConnection mWaivedBinding = null;
     // Incremented on addStrongBinding(), decremented on removeStrongBinding().
     private int mStrongBindingCount = 0;
+    // Moderate binding will make the service priority equal to the priority of a visible process
+    // while the app is in the foreground. It will stay bound only while the app is in the
+    // foreground to protect a background process from the system out-of-memory killer.
+    private ChildServiceConnection mModerateBinding = null;
 
     // Linker-related parameters.
     private ChromiumLinkerParams mLinkerParams = null;
 
     private final boolean mAlwaysInForeground;
 
-    private static final String TAG = "ChildProcessConnection";
+    private static final String TAG = "cr.ChildProcessConnect";
 
     private static class ConnectionParams {
         final String[] mCommandLine;
@@ -212,6 +216,7 @@ public class ChildProcessConnectionImpl implements ChildProcessConnection {
                 Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT);
         mWaivedBinding = new ChildServiceConnection(
                 Context.BIND_AUTO_CREATE | Context.BIND_WAIVE_PRIORITY);
+        mModerateBinding = new ChildServiceConnection(Context.BIND_AUTO_CREATE);
     }
 
     @Override
@@ -297,6 +302,7 @@ public class ChildProcessConnectionImpl implements ChildProcessConnection {
             mInitialBinding.unbind();
             mStrongBinding.unbind();
             mWaivedBinding.unbind();
+            mModerateBinding.unbind();
             mStrongBindingCount = 0;
             if (mService != null) {
                 mService = null;
@@ -398,6 +404,8 @@ public class ChildProcessConnectionImpl implements ChildProcessConnection {
 
             mStrongBindingCount = 0;
             mStrongBinding.unbind();
+
+            mModerateBinding.unbind();
         }
     }
 
@@ -430,6 +438,35 @@ public class ChildProcessConnectionImpl implements ChildProcessConnection {
         }
     }
 
+    @Override
+    public boolean isModerateBindingBound() {
+        synchronized (mLock) {
+            return mModerateBinding.isBound();
+        }
+    }
+
+    @Override
+    public void addModerateBinding() {
+        synchronized (mLock) {
+            if (mService == null) {
+                Log.w(TAG, "The connection is not bound for " + mPid);
+                return;
+            }
+            mModerateBinding.bind(null);
+        }
+    }
+
+    @Override
+    public void removeModerateBinding() {
+        synchronized (mLock) {
+            if (mService == null) {
+                Log.w(TAG, "The connection is not bound for " + mPid);
+                return;
+            }
+            mModerateBinding.unbind();
+        }
+    }
+
     @VisibleForTesting
     public boolean crashServiceForTesting() throws RemoteException {
         try {