Move FdEventsReader to the shared area.

This is necessary both in the network stack app and the
framework.

Test: FrameworksNetTests
Change-Id: I48af0ab29405501f0581a6c0c9ce6e5d4a32c8b4
diff --git a/packages/NetworkStack/src/android/net/util/FdEventsReader.java b/core/java/android/net/shared/FdEventsReader.java
similarity index 93%
rename from packages/NetworkStack/src/android/net/util/FdEventsReader.java
rename to core/java/android/net/shared/FdEventsReader.java
index 8bbf449..5ccc560 100644
--- a/packages/NetworkStack/src/android/net/util/FdEventsReader.java
+++ b/core/java/android/net/shared/FdEventsReader.java
@@ -14,10 +14,10 @@
  * limitations under the License.
  */
 
-package android.net.util;
+package android.net.shared;
 
-import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
 import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_ERROR;
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -63,6 +63,7 @@
  * All public methods MUST only be called from the same thread with which
  * the Handler constructor argument is associated.
  *
+ * @param <BufferType> the type of the buffer used to read data.
  * @hide
  */
 public abstract class FdEventsReader<BufferType> {
@@ -89,6 +90,7 @@
         mBuffer = buffer;
     }
 
+    /** Start this FdEventsReader. */
     public void start() {
         if (onCorrectThread()) {
             createAndRegisterFd();
@@ -100,6 +102,7 @@
         }
     }
 
+    /** Stop this FdEventsReader and destroy the file descriptor. */
     public void stop() {
         if (onCorrectThread()) {
             unregisterAndDestroyFd();
@@ -112,18 +115,25 @@
     }
 
     @NonNull
-    public Handler getHandler() { return mHandler; }
+    public Handler getHandler() {
+        return mHandler;
+    }
 
     protected abstract int recvBufSize(@NonNull BufferType buffer);
 
-    public int recvBufSize() { return recvBufSize(mBuffer); }
+    /** Returns the size of the receive buffer. */
+    public int recvBufSize() {
+        return recvBufSize(mBuffer);
+    }
 
     /**
      * Get the number of successful calls to {@link #readPacket(FileDescriptor, Object)}.
      *
      * <p>A call was successful if {@link #readPacket(FileDescriptor, Object)} returned a value > 0.
      */
-    public final long numPacketsReceived() { return mPacketsReceived; }
+    public final long numPacketsReceived() {
+        return mPacketsReceived;
+    }
 
     /**
      * Subclasses MUST create the listening socket here, including setting
@@ -199,7 +209,9 @@
         onStart();
     }
 
-    private boolean isRunning() { return (mFd != null) && mFd.valid(); }
+    private boolean isRunning() {
+        return (mFd != null) && mFd.valid();
+    }
 
     // Keep trying to read until we get EAGAIN/EWOULDBLOCK or some fatal error.
     private boolean handleInput() {
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpPacketListener.java b/packages/NetworkStack/src/android/net/dhcp/DhcpPacketListener.java
index dce8b61..eac8d2a 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpPacketListener.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpPacketListener.java
@@ -18,7 +18,7 @@
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.net.util.FdEventsReader;
+import android.net.shared.FdEventsReader;
 import android.os.Handler;
 import android.system.Os;
 
diff --git a/packages/NetworkStack/src/android/net/util/PacketReader.java b/packages/NetworkStack/src/android/net/util/PacketReader.java
index 4aec6b6..94b1e9f 100644
--- a/packages/NetworkStack/src/android/net/util/PacketReader.java
+++ b/packages/NetworkStack/src/android/net/util/PacketReader.java
@@ -18,6 +18,7 @@
 
 import static java.lang.Math.max;
 
+import android.net.shared.FdEventsReader;
 import android.os.Handler;
 import android.system.Os;