Bug 1620145: Part 1 - Support content process prioritization in GeckoView; r=geckoview-reviewers,agi

We change a few things in this patch:

* We modify `ServiceAllocator` to support multiple bindings:
    * Since Android distinguishes unique bindings via unique `ServiceConnection`
      objects, we add a `Binding` class that provides that bare-bones
      distinction but just forwards the `ServiceConnection` callbacks to its
      `InstanceInfo` owner.
    * Each `InstanceInfo` represents one content process instance, and it holds
      references to between 0 and 3 `Binding` objects, one for each possible
      priority level.
    * After changing the current priority level of an `InstanceInfo`, we call
      the `updateBindings` method to add or drop bindings as necessary to
      effect the correct level.
    * We add code to support the new `Context.updateServiceGroup` API starting
      with Android 10. Essentially it describes to Android the relative
      importance of multiple services running within the same priority level
      (think of it like how we rank our P2 bugs).
* We add `GeckoProcessManager.setProcessPriority` to receive prioritization
  changes from Gecko and wire that into the `ServiceAllocator`. We start new
  processes with `PriorityLevel.BACKGROUND` and then Gecko subsequently adjusts
  as necessary.
* Once this lands we must also set `dom.ipc.processPriorityManager.enabled=true`
  to experiment with e10s-multi.

Differential Revision: https://phabricator.services.mozilla.com/D68419

--HG--
extra : moz-landing-system : lando

mobile/android/geckoview/src/main/java/org/mozilla/gecko/process/GeckoProcessManager.java

@@ -115,11 +115,6 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
             mPid = INVALID_PID;
         }
 
-        public ChildConnection(@NonNull final ServiceAllocator allocator,
-                               @NonNull final GeckoProcessType type) {
-            this(allocator, type, PriorityLevel.FOREGROUND);
-        }
-
         public int getPid() throws RemoteException {
             XPCOMEventTarget.assertOnLauncherThread();
             if (mChild == null) {
@@ -215,7 +210,7 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
             // This could end up using IPC, so do it before we unbind.
             final int pid = getPidFallible();
 
-            doUnbind();
+            unbindService();
 
             if (pid != INVALID_PID) {
                 Process.killProcess(pid);
@@ -224,24 +219,6 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
             return GeckoResult.fromValue(null);
         }
 
-        private void clearConnectionInfo() {
-            // NB: This must happen *before* resetting mPid!
-            GeckoProcessManager.INSTANCE.mConnections.removeConnection(this);
-
-            mChild = null;
-            mPid = INVALID_PID;
-        }
-
-        private void doUnbind() {
-            try {
-                unbindService();
-            } catch (IllegalArgumentException e) {
-                // The binding was already dead. That's okay.
-            } finally {
-                clearConnectionInfo();
-            }
-        }
-
         @Override
         protected void onBinderConnected(final IBinder service) {
             XPCOMEventTarget.assertOnLauncherThread();
@@ -256,13 +233,12 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
         }
 
         @Override
-        protected void onBinderConnectionLost() {
-            XPCOMEventTarget.assertOnLauncherThread();
+        protected void onReleaseResources() {
+            // NB: This must happen *before* resetting mPid!
+            GeckoProcessManager.INSTANCE.mConnections.removeConnection(this);
 
-            // The binding has lost its connection, but the binding itself might still be active.
-            // Gecko itself will request a process restart, so here we attempt to unbind so that
-            // Android does not try to automatically restart and reconnect the service.
-            doUnbind();
+            mChild = null;
+            mPid = INVALID_PID;
         }
     }
 
@@ -375,11 +351,12 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
             XPCOMEventTarget.assertOnLauncherThread();
 
             if (mNonStartedContentConnections.isEmpty()) {
-                // Only FOREGROUND supported right now
-                return getNewContentConnection(PriorityLevel.FOREGROUND);
+                // Initially start at BACKGROUND; Gecko will adjust as necessary.
+                return getNewContentConnection(PriorityLevel.BACKGROUND);
             }
 
-            return mNonStartedContentConnections.removeAt(mNonStartedContentConnections.size() - 1);
+            final ChildConnection conn = mNonStartedContentConnections.removeAt(mNonStartedContentConnections.size() - 1);
+            return conn;
         }
 
         /**
@@ -393,7 +370,7 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
 
             ChildConnection connection = mNonContentConnections.get(type);
             if (connection == null) {
-                connection = new ChildConnection(mServiceAllocator, type);
+                connection = new ChildConnection(mServiceAllocator, type, PriorityLevel.FOREGROUND);
                 mNonContentConnections.put(type, connection);
             }
             return connection;
@@ -415,7 +392,7 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
          */
         public ChildConnection getConnectionForPreload(@NonNull final GeckoProcessType type) {
             if (type == GeckoProcessType.CONTENT) {
-                final ChildConnection conn = getNewContentConnection(PriorityLevel.FOREGROUND);
+                final ChildConnection conn = getNewContentConnection(PriorityLevel.BACKGROUND);
                 mNonStartedContentConnections.add(conn);
                 return conn;
             }
@@ -473,6 +450,20 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
         conn.unbind();
     }
 
+    @WrapForJNI
+    private static void setProcessPriority(@NonNull final Selector selector,
+                                           @NonNull final PriorityLevel priorityLevel,
+                                           final int relativeImportance) {
+        XPCOMEventTarget.runOnLauncherThread(() -> {
+            final ChildConnection conn = INSTANCE.mConnections.getExistingConnection(selector);
+            if (conn == null) {
+                return;
+            }
+
+            conn.setPriorityLevel(priorityLevel, relativeImportance);
+        });
+    }
+
     @WrapForJNI
     private static GeckoResult<Integer> start(final GeckoProcessType type,
                                               final String[] args,

mobile/android/geckoview/src/main/java/org/mozilla/gecko/process/ServiceAllocator.java

@@ -4,8 +4,8 @@
 
 package org.mozilla.gecko.process;
 
+import org.mozilla.gecko.annotation.WrapForJNI;
 import org.mozilla.gecko.GeckoAppShell;
-import org.mozilla.gecko.util.IXPCOMEventTarget;
 import org.mozilla.gecko.util.XPCOMEventTarget;
 
 import android.content.ComponentName;
@@ -13,23 +13,29 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ServiceInfo;
 import android.content.ServiceConnection;
+import android.os.Build;
 import android.os.IBinder;
 import android.support.annotation.NonNull;
+import android.util.Log;
 
-import java.lang.reflect.Method;
 import java.util.BitSet;
 import java.util.concurrent.Executor;
+import java.util.EnumMap;
+import java.util.Map.Entry;
 
 /* package */ final class ServiceAllocator {
+    private static final String LOGTAG = "ServiceAllocator";
     private static final int MAX_NUM_ISOLATED_CONTENT_SERVICES = 50;
 
-    private static final Method sBindIsolatedService = resolveBindIsolatedService();
-    private static final Method sBindServiceWithExecutor = resolveBindServiceWithExecutor();
+    private static boolean hasQApis() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q;
+    }
 
     /**
      * Possible priority levels that are available to child services. Each one maps to a flag that
      * is passed into Context.bindService().
      */
+    @WrapForJNI
     public static enum PriorityLevel {
         FOREGROUND (Context.BIND_IMPORTANT),
         BACKGROUND (0),
@@ -46,28 +52,125 @@ import java.util.concurrent.Executor;
         }
     }
 
+    private interface BindServiceDelegate {
+        boolean bindService(ServiceConnection binding, PriorityLevel priority);
+        String getServiceName();
+    }
+
     /**
      * Abstract class that holds the essential per-service data that is required to work with
      * ServiceAllocator. ServiceAllocator clients should extend this class when implementing their
      * per-service connection objects.
      */
-    public static abstract class InstanceInfo implements ServiceConnection {
+    public static abstract class InstanceInfo {
+        private class Binding implements ServiceConnection {
+            /**
+             * This implementation of ServiceConnection.onServiceConnected simply bounces the
+             * connection notification over to the launcher thread (if it is not already on it).
+             */
+            @Override
+            public final void onServiceConnected(final ComponentName name,
+                                                 final IBinder service) {
+                XPCOMEventTarget.runOnLauncherThread(() -> {
+                    onBinderConnectedInternal(service);
+                });
+            }
+
+            /**
+             * This implementation of ServiceConnection.onServiceDisconnected simply bounces the
+             * disconnection notification over to the launcher thread (if it is not already on it).
+             */
+            @Override
+            public final void onServiceDisconnected(final ComponentName name) {
+                XPCOMEventTarget.runOnLauncherThread(() -> {
+                    onBinderConnectionLostInternal();
+                });
+            }
+        }
+
+        private class DefaultBindDelegate implements BindServiceDelegate {
+            @Override
+            public boolean bindService(@NonNull final ServiceConnection binding, @NonNull final PriorityLevel priority) {
+                final Context context = GeckoAppShell.getApplicationContext();
+                final Intent intent = new Intent();
+                intent.setClassName(context, getServiceName());
+                return bindServiceDefault(context, intent, binding, getAndroidFlags(priority));
+            }
+
+            @Override
+            public String getServiceName() {
+                return getSvcClassNameDefault(InstanceInfo.this);
+            }
+        }
+
+        private class IsolatedBindDelegate implements BindServiceDelegate {
+            @Override
+            public boolean bindService(@NonNull final ServiceConnection binding, @NonNull final PriorityLevel priority) {
+                final Context context = GeckoAppShell.getApplicationContext();
+                final Intent intent = new Intent();
+                intent.setClassName(context, getServiceName());
+                return bindServiceIsolated(context, intent, getAndroidFlags(priority),
+                                           getIdAsString(), binding);
+            }
+
+            @Override
+            public String getServiceName() {
+                return ServiceUtils.buildIsolatedSvcName(getType());
+            }
+        }
+
         private final ServiceAllocator mAllocator;
         private final GeckoProcessType mType;
         private final Integer mId;
-        // Priority level is not yet adjustable, so mPriority is final for now
-        private final PriorityLevel mPriority;
+        private final EnumMap<PriorityLevel, Binding> mBindings;
+        private final BindServiceDelegate mBindDelegate;
+
+        private boolean mCalledConnected = false;
+        private boolean mCalledConnectionLost = false;
+        private boolean mIsDefunct = false;
+
+        private PriorityLevel mCurrentPriority;
+        private int mRelativeImportance = 0;
 
         protected InstanceInfo(@NonNull final ServiceAllocator allocator, @NonNull final GeckoProcessType type,
                                @NonNull final PriorityLevel priority) {
             mAllocator = allocator;
             mType = type;
             mId = mAllocator.allocate(type);
-            mPriority = priority;
+            mBindings = new EnumMap<PriorityLevel, Binding>(PriorityLevel.class);
+            mBindDelegate = getBindServiceDelegate();
+
+            mCurrentPriority = priority;
+        }
+
+        private BindServiceDelegate getBindServiceDelegate() {
+            if (mType != GeckoProcessType.CONTENT) {
+                // Non-content services just use default binding
+                return this.new DefaultBindDelegate();
+            }
+
+            // Content services defer to the alloc policy
+            return mAllocator.mContentAllocPolicy.getBindServiceDelegate(this);
         }
 
         public PriorityLevel getPriorityLevel() {
-            return mPriority;
+            XPCOMEventTarget.assertOnLauncherThread();
+            return mCurrentPriority;
+        }
+
+        public boolean setPriorityLevel(@NonNull final PriorityLevel newPriority,
+                                        final int relativeImportance) {
+            XPCOMEventTarget.assertOnLauncherThread();
+            mCurrentPriority = newPriority;
+            mRelativeImportance = relativeImportance;
+
+            // If we haven't bound yet then we can just return
+            if (mBindings.size() == 0) {
+                return true;
+            }
+
+            // Otherwise we need to update our bindings
+            return updateBindings();
         }
 
         /**
@@ -98,72 +201,191 @@ import java.util.concurrent.Executor;
         }
 
         protected boolean bindService() {
-            return mAllocator.bindService(this);
+            if (mIsDefunct) {
+                throw new AssertionError("Attempt to bind a defunct InstanceInfo!");
+            }
+
+            return updateBindings();
         }
 
+        /**
+         * Unbinds the service described by |this| and releases our unique ID. This method may
+         * safely be called multiple times even if we are already defunct.
+         */
         protected void unbindService() {
-            mAllocator.unbindService(this);
-        }
+            XPCOMEventTarget.assertOnLauncherThread();
 
-        /**
-         * This implementation of ServiceConnection.onServiceConnected simply bounces the
-         * connection notification over to the launcher thread (if it is not already on it).
-         */
-        @Override
-        public final void onServiceConnected(final ComponentName name,
-                                             final IBinder service) {
-            final IXPCOMEventTarget launcherThread = XPCOMEventTarget.launcherThread();
-            if (launcherThread.isOnCurrentThread()) {
-                // If we were able to specify an Executor during binding then we are already on
-                // the launcher thread; there is no reason to bounce through its event queue.
-                onBinderConnected(service);
+            // This could happen if a service death races with our attempt to shut it down.
+            if (mIsDefunct) {
                 return;
             }
 
-            launcherThread.execute(() -> {
-                onBinderConnected(service);
-            });
-        }
+            final Context context = GeckoAppShell.getApplicationContext();
 
-        /**
-         * This implementation of ServiceConnection.onServiceDisconnected simply bounces the
-         * disconnection notification over to the launcher thread (if it is not already on it).
-         */
-        @Override
-        public final void onServiceDisconnected(final ComponentName name) {
-            final IXPCOMEventTarget launcherThread = XPCOMEventTarget.launcherThread();
-            if (launcherThread.isOnCurrentThread()) {
-                // If we were able to specify an Executor during binding then we are already on
-                // the launcher thread; there is no reason to bounce through its event queue.
-                onBinderConnectionLost();
+            RuntimeException lastException = null;
+
+            // Make a clone of mBindings to iterate over since we're going to mutate the original
+            final EnumMap<PriorityLevel, Binding> cloned = mBindings.clone();
+            for (final Entry<PriorityLevel, Binding> entry : cloned.entrySet()) {
+                try {
+                    context.unbindService(entry.getValue());
+                } catch (final IllegalArgumentException e) {
+                    // The binding was already dead. That's okay.
+                } catch (final RuntimeException e) {
+                    lastException = e;
+                    continue;
+                }
+
+                mBindings.remove(entry.getKey());
+            }
+
+            if (mBindings.size() == 0) {
+                mIsDefunct = true;
+                mAllocator.release(this);
+                onReleaseResources();
                 return;
             }
 
-            launcherThread.execute(() -> {
-                onBinderConnectionLost();
-            });
+            final String svcName = mBindDelegate.getServiceName();
+            final StringBuilder builder = new StringBuilder("Unable to release service\"");
+            builder.append(svcName).append("\" because ").append(mBindings.size()).append(" bindings could not be dropped");
+            Log.e(LOGTAG, builder.toString());
+
+            if (lastException != null) {
+                throw lastException;
+            }
+        }
+
+        private void onBinderConnectedInternal(@NonNull final IBinder service) {
+            XPCOMEventTarget.assertOnLauncherThread();
+            // We only care about the first time this is called; subsequent bindings can be ignored.
+            if (mCalledConnected) {
+                return;
+            }
+
+            mCalledConnected = true;
+
+            onBinderConnected(service);
+        }
+
+        private void onBinderConnectionLostInternal() {
+            XPCOMEventTarget.assertOnLauncherThread();
+            // We only care about the first time this is called; subsequent connection errors can be ignored.
+            if (mCalledConnectionLost) {
+                return;
+            }
+
+            mCalledConnectionLost = true;
+
+            onBinderConnectionLost();
         }
 
-        /**
-         * Called on the launcher thread to inform the client that the service's Binder has been
-         * connected. This method is named differently from its ServiceConnection counterpart for
-         * the sake of clarity.
-         */
         protected abstract void onBinderConnected(@NonNull final IBinder service);
+        protected abstract void onReleaseResources();
+
+        // Optionally overridable by subclasses, but this is a sane default
+        protected void onBinderConnectionLost() {
+            // The binding has lost its connection, but the binding itself might still be active.
+            // Gecko itself will request a process restart, so here we attempt to unbind so that
+            // Android does not try to automatically restart and reconnect the service.
+            unbindService();
+        }
 
         /**
-         * Called on the launcher thread to inform the client that the service's Binder has been
-         * lost. This method is named differently from its ServiceConnection counterpart for the
-         * sake of clarity. Note that this method is *not* called during a clean unbind.
+         * This function relies on the fact that the PriorityLevel enum is ordered from highest
+         * priority to lowest priority. We examine the ordinal of the current priority setting,
+         * and then iterate across all possible priority levels, adjusting as necessary.
+         * Any priority levels whose ordinals are less than then current priority level ordinal must
+         * be unbound, while all priority levels whose ordinals are greater than or equal to the
+         * current priority level ordinal must be bound.
          */
-        protected abstract void onBinderConnectionLost();
+        private boolean updateBindings() {
+            XPCOMEventTarget.assertOnLauncherThread();
+            int numBindSuccesses = 0;
+            int numBindFailures = 0;
+            int numUnbindSuccesses = 0;
+            int numUnbindFailures = 0;
+
+            final Context context = GeckoAppShell.getApplicationContext();
+
+            // This code assumes that the order of the PriorityLevel enum is highest to lowest
+            final int curPriorityOrdinal = mCurrentPriority.ordinal();
+            final PriorityLevel[] levels = PriorityLevel.values();
+
+            for (int curLevelIdx = 0; curLevelIdx < levels.length; ++curLevelIdx) {
+                final PriorityLevel curLevel = levels[curLevelIdx];
+                final Binding existingBinding = mBindings.get(curLevel);
+                final boolean hasExistingBinding = existingBinding != null;
+
+                if (curLevelIdx < curPriorityOrdinal) {
+                    // Remove if present
+                    if (hasExistingBinding) {
+                        try {
+                            context.unbindService(existingBinding);
+                            ++numUnbindSuccesses;
+                            mBindings.remove(curLevel);
+                        } catch (final IllegalArgumentException e) {
+                            // The binding was already dead. That's okay.
+                            ++numUnbindSuccesses;
+                            mBindings.remove(curLevel);
+                        } catch (final Throwable e) {
+                            final String svcName = mBindDelegate.getServiceName();
+                            final StringBuilder builder = new StringBuilder(svcName);
+                            builder.append(" updateBindings failed to unbind due to exception: ").append(e);
+                            Log.w(LOGTAG, builder.toString());
+                            ++numUnbindFailures;
+                        }
+                    }
+                } else {
+                    // Normally we only need to do a bind if we do not yet have an existing binding
+                    // for this priority level.
+                    boolean bindNeeded = !hasExistingBinding;
+
+                    // We only update the service group when the binding for this level already
+                    // exists and no binds have occurred yet during the current updateBindings call.
+                    if (hasExistingBinding && hasQApis() && (numBindSuccesses + numBindFailures) == 0) {
+                        // NB: Right now we're passing 0 as the |group| argument, indicating that
+                        // the process is not grouped with any other processes. Once we support
+                        // Fission we should re-evaluate this.
+                        context.updateServiceGroup(existingBinding, 0, mRelativeImportance);
+                        // Now we need to call bindService with the existing binding to make this
+                        // change take effect.
+                        bindNeeded = true;
+                    }
+
+                    if (bindNeeded) {
+                        final Binding useBinding = hasExistingBinding ? existingBinding : this.new Binding();
+                        if (mBindDelegate.bindService(useBinding, curLevel)) {
+                            ++numBindSuccesses;
+                            if (!hasExistingBinding) {
+                                mBindings.put(curLevel, useBinding);
+                            }
+                        } else {
+                            ++numBindFailures;
+                        }
+                    }
+                }
+            }
+
+            final String svcName = mBindDelegate.getServiceName();
+            final StringBuilder builder = new StringBuilder(svcName);
+            builder.append(" updateBindings: ").append(mCurrentPriority).append(" priority, ")
+                   .append(mRelativeImportance).append(" importance, ")
+                   .append(numBindSuccesses).append(" successful binds, ")
+                   .append(numBindFailures).append(" failed binds, ")
+                   .append(numUnbindSuccesses).append(" successful unbinds, ")
+                   .append(numUnbindFailures).append(" failed unbinds");
+            Log.d(LOGTAG, builder.toString());
+
+            return numBindFailures == 0 && numUnbindFailures == 0;
+        }
     }
 
     private interface ContentAllocationPolicy {
         /**
-         * Bind a new content service.
+         * @return BindServiceDelegate that will be used for binding a new content service.
          */
-        boolean bindService(Context context, InstanceInfo info);
+        BindServiceDelegate getBindServiceDelegate(InstanceInfo info);
 
         /**
          * Allocate an unused service ID for use by the caller.
@@ -192,13 +414,9 @@ import java.util.concurrent.Executor;
             mAllocator = new BitSet(mMaxNumSvcs);
         }
 
-        /**
-         * This implementation of bindService uses the default implementation as provided by
-         * ServiceAllocator.
-         */
         @Override
-        public boolean bindService(@NonNull final Context context, @NonNull final InstanceInfo info) {
-            return ServiceAllocator.bindServiceDefault(context, ServiceAllocator.getSvcClassNameDefault(info), info);
+        public BindServiceDelegate getBindServiceDelegate(@NonNull final InstanceInfo info) {
+            return info.new DefaultBindDelegate();
         }
 
         @Override
@@ -240,13 +458,9 @@ import java.util.concurrent.Executor;
         private int mNextIsolatedSvcId = 0;
         private int mCurNumIsolatedSvcs = 0;
 
-        /**
-         * This implementation of bindService uses the isolated bindService implementation as
-         * provided by ServiceAllocator.
-         */
         @Override
-        public boolean bindService(@NonNull final Context context, @NonNull final InstanceInfo info) {
-            return ServiceAllocator.bindServiceIsolated(context, ServiceUtils.buildIsolatedSvcName(info.getType()), info);
+        public BindServiceDelegate getBindServiceDelegate(@NonNull final InstanceInfo info) {
+            return info.new IsolatedBindDelegate();
         }
 
         /**
@@ -282,37 +496,6 @@ import java.util.concurrent.Executor;
      */
     private ContentAllocationPolicy mContentAllocPolicy = null;
 
-    /**
-     * Clients should call this method to bind their services. This method automagically does the
-     * right things depending on the state of info.
-     * @param info The InstanceInfo-derived object that contains essential information for setting
-     * up the child service.
-     */
-    public boolean bindService(@NonNull final InstanceInfo info) {
-        XPCOMEventTarget.assertOnLauncherThread();
-        final Context context = GeckoAppShell.getApplicationContext();
-        if (!info.isContent()) {
-            // Non-content services just use standard binding.
-            return bindServiceDefault(context, getSvcClassNameDefault(info), info);
-        }
-
-        // Content services defer to the alloc policy to determine how to bind.
-        return mContentAllocPolicy.bindService(context, info);
-    }
-
-    /**
-     * Unbinds the service described by |info| and releases its unique ID.
-     */
-    public void unbindService(@NonNull final InstanceInfo info) {
-        XPCOMEventTarget.assertOnLauncherThread();
-        final Context context = GeckoAppShell.getApplicationContext();
-        try {
-            context.unbindService(info);
-        } finally {
-            release(info);
-        }
-    }
-
     /**
      * Allocate a service ID.
      * @param type The type of service.
@@ -359,7 +542,7 @@ import java.util.concurrent.Executor;
      * @return true if this service type may use isolated binding, otherwise false.
      */
     private static boolean canBindIsolated(@NonNull final GeckoProcessType type) {
-        if (sBindIsolatedService == null) {
+        if (!hasQApis()) {
             return false;
         }
 
@@ -386,67 +569,18 @@ import java.util.concurrent.Executor;
      * Wrapper for bindService() that utilizes the Context.bindService() overload that accepts an
      * Executor argument, when available. Otherwise it falls back to the legacy overload.
      */
-    private static boolean bindServiceDefault(@NonNull final Context context, @NonNull final String svcClassName, @NonNull final InstanceInfo info) {
-        final Intent intent = new Intent();
-        intent.setClassName(context, svcClassName);
-
-        if (sBindServiceWithExecutor != null) {
-            return bindServiceWithExecutor(context, intent, info);
+    private static boolean bindServiceDefault(@NonNull final Context context, @NonNull final Intent intent, @NonNull final ServiceConnection conn, final int flags) {
+        if (hasQApis()) {
+            // We always specify the launcher thread as our Executor.
+            return context.bindService(intent, flags, XPCOMEventTarget.launcherThread(), conn);
         }
 
-        return context.bindService(intent, info, getAndroidFlags(info.getPriorityLevel()));
+        return context.bindService(intent, conn, flags);
     }
 
-    /**
-     * Wrapper that calls the reflected Context.bindIsolatedService() method.
-     */
-    private static boolean bindServiceIsolated(@NonNull final Context context, @NonNull final String svcClassName, @NonNull final InstanceInfo info) {
-        final Intent intent = new Intent();
-        intent.setClassName(context, svcClassName);
-
-        final String instanceId = info.getIdAsString();
-
-        try {
-            final Boolean result = (Boolean) sBindIsolatedService.invoke(context, intent, getAndroidFlags(info.getPriorityLevel()),
-                                                                         instanceId, XPCOMEventTarget.launcherThread(), info);
-            return result.booleanValue();
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    /**
-     * Wrapper that calls the reflected Context.bindService() overload that accepts an Executor argument.
-     * We always specify the launcher thread as our Executor.
-     */
-    private static boolean bindServiceWithExecutor(@NonNull final Context context, @NonNull final Intent intent, @NonNull final InstanceInfo info) {
-        try {
-            final Boolean result = (Boolean) sBindServiceWithExecutor.invoke(context, intent, getAndroidFlags(info.getPriorityLevel()),
-                                                                             XPCOMEventTarget.launcherThread(), info);
-            return result.booleanValue();
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    private static Method resolveBindIsolatedService() {
-        try {
-            return Context.class.getDeclaredMethod("bindIsolatedService", Intent.class, Integer.class, String.class, Executor.class, ServiceConnection.class);
-        } catch (NoSuchMethodException e) {
-            return null;
-        } catch (Throwable e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    private static Method resolveBindServiceWithExecutor() {
-        try {
-            return Context.class.getDeclaredMethod("bindService", Intent.class, Integer.class, Executor.class, ServiceConnection.class);
-        } catch (NoSuchMethodException e) {
-            return null;
-        } catch (Throwable e) {
-            throw new RuntimeException(e);
-        }
+    private static boolean bindServiceIsolated(@NonNull final Context context, @NonNull final Intent intent, final int flags, @NonNull final String instanceId, @NonNull final ServiceConnection conn) {
+        // We always specify the launcher thread as our Executor.
+        return context.bindIsolatedService(intent, flags, instanceId, XPCOMEventTarget.launcherThread(), conn);
     }
 }
 

mobile/android/geckoview/src/main/java/org/mozilla/gecko/util/XPCOMEventTarget.java

@@ -10,6 +10,8 @@ import org.mozilla.gecko.GeckoThread;
 import org.mozilla.gecko.mozglue.JNIObject;
 import org.mozilla.geckoview.BuildConfig;
 
+import android.support.annotation.NonNull;
+
 /**
  * Wrapper for nsIEventTarget, enabling seamless dispatch of java runnables to
  * Gecko event queues.
@@ -37,6 +39,21 @@ public final class XPCOMEventTarget extends JNIObject implements IXPCOMEventTarg
     }
     private static IXPCOMEventTarget mLauncherThread = null;
 
+    /**
+     * Runs the provided runnable on the launcher thread. If this method is called from the launcher
+     * thread itself, the runnable will be executed immediately and synchronously.
+     */
+    public static void runOnLauncherThread(@NonNull final Runnable runnable) {
+        final IXPCOMEventTarget launcherThread = launcherThread();
+        if (launcherThread.isOnCurrentThread()) {
+            // We're already on the launcher thread, just execute the runnable
+            runnable.run();
+            return;
+        }
+
+        launcherThread.execute(runnable);
+    }
+
     public static void assertOnLauncherThread() {
         if (BuildConfig.DEBUG && !launcherThread().isOnCurrentThread()) {
             throw new AssertionError("Expected to be running on XPCOM launcher thread");