Fix memory leaks caused by the android framework

app/src/main/java/acr/browser/lightning/app/BrowserApp.java

@@ -1,9 +1,11 @@
 package acr.browser.lightning.app;
 
+import android.app.Activity;
 import android.app.Application;
 import android.content.Context;
 import android.os.Build;
 import android.support.annotation.NonNull;
+import android.util.Log;
 import android.webkit.WebView;
 
 import com.squareup.leakcanary.LeakCanary;
@@ -16,9 +18,12 @@ import javax.inject.Inject;
 
 import acr.browser.lightning.BuildConfig;
 import acr.browser.lightning.preference.PreferenceManager;
+import acr.browser.lightning.utils.MemoryLeakUtils;
 
 public class BrowserApp extends Application {
 
+    private static final String TAG = BrowserApp.class.getSimpleName();
+
     private static AppComponent mAppComponent;
     private static final Executor mIOThread = Executors.newSingleThreadExecutor();
     private static final Executor mTaskThread = Executors.newCachedThreadPool();
@@ -38,6 +43,14 @@ public class BrowserApp extends Application {
         if (!isRelease() && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
             WebView.setWebContentsDebuggingEnabled(true);
         }
+
+        registerActivityLifecycleCallbacks(new MemoryLeakUtils.LifecycleAdapter() {
+            @Override
+            public void onActivityDestroyed(Activity activity) {
+                Log.d(TAG, "Cleaning up after the Android framework");
+                MemoryLeakUtils.clearNextServedView(BrowserApp.this);
+            }
+        });
     }
 
     @NonNull

app/src/main/java/acr/browser/lightning/utils/MemoryLeakUtils.java

@@ -0,0 +1,80 @@
+package acr.browser.lightning.utils;
+
+import android.app.Activity;
+import android.app.Application;
+import android.content.Context;
+import android.os.Build;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.util.Log;
+import android.view.inputmethod.InputMethodManager;
+
+import java.lang.reflect.Method;
+
+public class MemoryLeakUtils {
+
+    private static final String TAG = MemoryLeakUtils.class.getSimpleName();
+
+    private static Method sFinishInputLocked = null;
+
+    /**
+     * Clears the mNextServedView and mServedView in
+     * InputMethodManager and keeps them from leaking.
+     *
+     * @param application the application needed to get
+     *                    the InputMethodManager that is
+     *                    leaking the views.
+     */
+    public static void clearNextServedView(@NonNull Application application) {
+
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
+            // This shouldn't be a problem on N
+            return;
+        }
+
+        InputMethodManager imm = (InputMethodManager) application.getSystemService(Context.INPUT_METHOD_SERVICE);
+
+        if (sFinishInputLocked == null) {
+            try {
+                sFinishInputLocked = InputMethodManager.class.getDeclaredMethod("finishInputLocked");
+            } catch (NoSuchMethodException e) {
+                Log.d(TAG, "Unable to find method in clearNextServedView", e);
+            }
+        }
+
+        if (sFinishInputLocked != null) {
+            sFinishInputLocked.setAccessible(true);
+            try {
+                sFinishInputLocked.invoke(imm);
+            } catch (Exception e) {
+                Log.d(TAG, "Unable to invoke method in clearNextServedView", e);
+            }
+        }
+
+    }
+
+    public static abstract class LifecycleAdapter implements Application.ActivityLifecycleCallbacks {
+        @Override
+        public void onActivityCreated(Activity activity, Bundle savedInstanceState) {}
+
+        @Override
+        public void onActivityStarted(Activity activity) {}
+
+        @Override
+        public void onActivityResumed(Activity activity) {}
+
+        @Override
+        public void onActivityPaused(Activity activity) {}
+
+        @Override
+        public void onActivityStopped(Activity activity) {}
+
+        @Override
+        public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}
+
+        @Override
+        public void onActivityDestroyed(Activity activity) {}
+    }
+
+
+}