android: Add method to kill child process

Add a kill method to ChildProcessConnection to force kill the service.
Also add a new field that keeps track of whether the process is killed
intentionally. Add a junit test to verify this.

Bug: 693484
Change-Id: Iaae9e82e611be97b9694fc8d67b23ba090220840
Reviewed-on: https://chromium-review.googlesource.com/1003635Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Jay Civelli <jcivelli@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550744}

base/android/java/src/org/chromium/base/process_launcher/ChildProcessConnection.java

@@ -215,11 +215,14 @@ public class ChildProcessConnection {
 
     // Indicates whether the connection only has the waived binding (if the connection is unbound,
     // it contains the state at time of unbinding).
-    private boolean mWaivedBoundOnly;
+    private volatile boolean mWaivedBoundOnly;
 
     // Set to true once unbind() was called.
     private boolean mUnbound;
 
+    // Indicate |kill()| was called to intentionally kill this process.
+    private volatile boolean mKilledByUs;
+
     public ChildProcessConnection(Context context, ComponentName serviceName, boolean bindToCaller,
             boolean bindAsExternalService, Bundle serviceBundle) {
         this(context, serviceName, bindToCaller, bindAsExternalService, serviceBundle,
@@ -380,6 +383,19 @@ public class ChildProcessConnection {
         notifyChildProcessDied();
     }
 
+    public void kill() {
+        assert isRunningOnLauncherThread();
+        IChildProcessService service = mService;
+        unbind();
+        try {
+            if (service != null) service.forceKill();
+        } catch (RemoteException e) {
+            // Intentionally ignore since we are killing it anyway.
+        }
+        mKilledByUs = true;
+        notifyChildProcessDied();
+    }
+
     private void onServiceConnectedOnLauncherThread(IBinder service) {
         assert isRunningOnLauncherThread();
         // A flag from the parent class ensures we run the post-connection logic only once
@@ -606,6 +622,16 @@ public class ChildProcessConnection {
         return mWaivedBoundOnly;
     }
 
+    /**
+     * @return true if the connection is intentionally killed by calling kill().
+     */
+    public boolean isKilledByUs() {
+        // WARNING: this method can be called from a thread other than the launcher thread.
+        // Note that it returns the current waived bound only state and is racy. This not really
+        // preventable without changing the caller's API, short of blocking.
+        return mKilledByUs;
+    }
+
     // Should be called every time the mInitialBinding or mStrongBinding are bound/unbound.
     private void updateWaivedBoundOnlyState() {
         if (!mUnbound) {
@@ -629,7 +655,7 @@ public class ChildProcessConnection {
 
     @VisibleForTesting
     public void crashServiceForTesting() throws RemoteException {
-        mService.crashIntentionallyForTesting();
+        mService.forceKill();
     }
 
     @VisibleForTesting

base/android/java/src/org/chromium/base/process_launcher/ChildProcessService.java

@@ -125,7 +125,7 @@ public abstract class ChildProcessService extends Service {
         }
 
         @Override
-        public void crashIntentionallyForTesting() {
+        public void forceKill() {
             assert mServiceBound;
             Process.killProcess(Process.myPid());
         }

base/android/java/src/org/chromium/base/process_launcher/IChildProcessService.aidl

@@ -18,6 +18,6 @@ interface IChildProcessService {
   oneway void setupConnection(in Bundle args, ICallbackInt pidCallback,
           in List<IBinder>  clientInterfaces);
 
-  // Asks the child service to crash so that we can test the termination logic.
-  oneway void crashIntentionallyForTesting();
+  // Forcefully kills the child process.
+  oneway void forceKill();
 }

base/android/junit/src/org/chromium/base/process_launcher/ChildProcessConnectionTest.java

@@ -322,4 +322,29 @@ public class ChildProcessConnectionTest {
         mConnectionPidCallback.call(34 /* pid */);
         verify(mConnectionCallback, times(1)).onConnected(connection);
     }
+
+    @Test
+    public void testKill() throws RemoteException {
+        ChildProcessConnection connection = createDefaultTestConnection();
+        assertNotNull(mFirstServiceConnection);
+        connection.start(false /* useStrongBinding */, null /* serviceCallback */);
+        mFirstServiceConnection.notifyServiceConnected(mChildProcessServiceBinder);
+        connection.setupConnection(
+                null /* connectionBundle */, null /* callback */, mConnectionCallback);
+        verify(mConnectionCallback, never()).onConnected(any());
+        ShadowLooper.runUiThreadTasks();
+        assertNotNull(mConnectionPidCallback);
+        mConnectionPidCallback.call(34 /* pid */);
+        verify(mConnectionCallback, times(1)).onConnected(connection);
+
+        // Add strong binding so that connection is oom protected.
+        connection.addStrongBinding();
+        Assert.assertFalse(connection.isWaivedBoundOnlyOrWasWhenDied());
+
+        // Kill and verify state.
+        connection.kill();
+        verify(mIChildProcessService).forceKill();
+        Assert.assertFalse(connection.isWaivedBoundOnlyOrWasWhenDied());
+        Assert.assertTrue(connection.isKilledByUs());
+    }
 }