Remove the unused ITetheringStatsProvider.

This is safe because :
• There are no longer any existing user of this class in AOSP or
  downstream
• Known previous uses by OEMs/vendors have been removed
• This class is now superseded by the better and more generic
  network stats provider, so that remaining uses if any can be
  retrofitted into this newer, better class

Test: TH
Bug: 64955351
Merged-In: I88fee389a3c768baf7c29096d2245734d9dd4fe8
Change-Id: I88fee389a3c768baf7c29096d2245734d9dd4fe8

core/java/android/net/ITetheringStatsProvider.aidl

@@ -1,39 +0,0 @@
-/*
- * Copyright (C) 2017 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package android.net;
-
-import android.net.NetworkStats;
-
-/**
- * Interface for NetworkManagementService to query tethering statistics and set data limits.
- *
- * TODO: this does not really need to be an interface since Tethering runs in the same process
- * as NetworkManagementService. Consider refactoring Tethering to use direct access to
- * NetworkManagementService instead of using INetworkManagementService, and then deleting this
- * interface.
- *
- * @hide
- */
-interface ITetheringStatsProvider {
-    // Sets the interface quota for the specified upstream interface. This is defined as the number
-    // of bytes, starting from zero and counting from now, after which data should stop being
-    // forwarded to/from the specified upstream. A value of QUOTA_UNLIMITED means there is no limit.
-    void setInterfaceQuota(String iface, long quotaBytes);
-
-    // Indicates that no data usage limit is set.
-    const int QUOTA_UNLIMITED = -1;
-}

core/java/android/os/INetworkManagementService.aidl

@@ -19,7 +19,6 @@ package android.os;
 
 import android.net.InterfaceConfiguration;
 import android.net.INetworkManagementEventObserver;
-import android.net.ITetheringStatsProvider;
 import android.net.Network;
 import android.net.NetworkStats;
 import android.net.RouteInfo;

services/core/java/com/android/server/NetworkManagementService.java

@@ -44,7 +44,6 @@ import android.net.ConnectivityManager;
 import android.net.INetd;
 import android.net.INetdUnsolicitedEventListener;
 import android.net.INetworkManagementEventObserver;
-import android.net.ITetheringStatsProvider;
 import android.net.InetAddresses;
 import android.net.InterfaceConfiguration;
 import android.net.InterfaceConfigurationParcel;
@@ -135,10 +134,6 @@ public class NetworkManagementService extends INetworkManagementService.Stub {
     private final RemoteCallbackList<INetworkManagementEventObserver> mObservers =
             new RemoteCallbackList<>();
 
-    @GuardedBy("mTetheringStatsProviders")
-    private final HashMap<ITetheringStatsProvider, String>
-            mTetheringStatsProviders = Maps.newHashMap();
-
     /**
      * If both locks need to be held, then they should be obtained in the order:
      * first {@link #mQuotaLock} and then {@link #mRulesLock}.
@@ -217,10 +212,6 @@ public class NetworkManagementService extends INetworkManagementService.Stub {
         mNetdUnsolicitedEventListener = new NetdUnsolicitedEventListener();
 
         mDeps.registerLocalService(new LocalService());
-
-        synchronized (mTetheringStatsProviders) {
-            mTetheringStatsProviders.put(new NetdTetheringStatsProvider(), "netd");
-        }
     }
 
     static NetworkManagementService create(Context context, Dependencies deps)
@@ -909,17 +900,6 @@ public class NetworkManagementService extends INetworkManagementService.Stub {
             } catch (RemoteException | ServiceSpecificException e) {
                 throw new IllegalStateException(e);
             }
-
-            synchronized (mTetheringStatsProviders) {
-                for (ITetheringStatsProvider provider : mTetheringStatsProviders.keySet()) {
-                    try {
-                        provider.setInterfaceQuota(iface, quotaBytes);
-                    } catch (RemoteException e) {
-                        Log.e(TAG, "Problem setting tethering data limit on provider " +
-                                mTetheringStatsProviders.get(provider) + ": " + e);
-                    }
-                }
-            }
         }
     }
 
@@ -942,17 +922,6 @@ public class NetworkManagementService extends INetworkManagementService.Stub {
             } catch (RemoteException | ServiceSpecificException e) {
                 throw new IllegalStateException(e);
             }
-
-            synchronized (mTetheringStatsProviders) {
-                for (ITetheringStatsProvider provider : mTetheringStatsProviders.keySet()) {
-                    try {
-                        provider.setInterfaceQuota(iface, ITetheringStatsProvider.QUOTA_UNLIMITED);
-                    } catch (RemoteException e) {
-                        Log.e(TAG, "Problem removing tethering data limit on provider " +
-                                mTetheringStatsProviders.get(provider) + ": " + e);
-                    }
-                }
-            }
         }
     }
 
@@ -1148,13 +1117,6 @@ public class NetworkManagementService extends INetworkManagementService.Stub {
         return true;
     }
 
-    private class NetdTetheringStatsProvider extends ITetheringStatsProvider.Stub {
-        @Override
-        public void setInterfaceQuota(String iface, long quotaBytes) {
-            // Do nothing. netd is already informed of quota changes in setInterfaceQuota.
-        }
-    }
-
     @Override
     public void setFirewallEnabled(boolean enabled) {
         enforceSystemUid();