Selectively perform JNI registration in render processes on Android.

content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content.app;
 
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.SurfaceTexture;
 import android.os.Binder;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.Process;
 import android.os.RemoteException;
 import android.view.Surface;
 
 import org.chromium.base.BaseSwitches;
 import org.chromium.base.CommandLine;
 import org.chromium.base.ContextUtils;
+import org.chromium.base.JNIUtils;
 import org.chromium.base.Log;
 import org.chromium.base.UnguessableToken;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.MainDex;
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.base.annotations.UsedByReflection;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.library_loader.Linker;
 import org.chromium.base.library_loader.ProcessInitException;
@@ skipping 153 matching lines @@
             public void run()  {
                 try {
                     // CommandLine must be initialized before everything else.
                     synchronized (mMainThread) {
                         while (mCommandLineParams == null) {
                             mMainThread.wait();
                         }
                     }
                     CommandLine.init(mCommandLineParams);
 
+                    if ("renderer".equals(CommandLine.getInstance().getSwitchValue("type"))) {

[Ted C, 2017/01/31 17:56:54]

Sad to kill your 100 char perfect line, but I think this should be:

if (ContentSwitches.SWITCH_RENDERER_PROCESS.equals(
        CommandLine.getInstance().getSwitchValue(
                ContentSwitches.SWITCH_PROCESS_TYPE))) {

Also, tangent...any idea why we have ContentSwitches.getSwitchValue and the
corresponding one in CommandLine?

[estevenson, 2017/01/31 18:56:41]

:(. Done.

Not sure, my best guess is that ContentSwitches.getSwitchValue was probably
added so that ChildProcessLauncher can use it
(https://cs.chromium.org/chromium/src/content/public/android/java/src/org/chro...)
since the CommandLine instance isn't created until the child process is set up?

+                        JNIUtils.enableSelectiveJniRegistration();
+                    }
+
                     Linker linker = null;
                     boolean requestedSharedRelro = false;
                     if (Linker.isUsed()) {
                         assert mLinkerParams != null;
                         linker = getLinker();
                         if (mLinkerParams.mWaitForSharedRelro) {
                             requestedSharedRelro = true;
                             linker.initServiceProcess(mLinkerParams.mBaseLoadAddress);
                         } else {
                             linker.disableSharedRelros();
@@ skipping 243 matching lines @@
     private static native void nativeInitChildProcessImpl(
             ChildProcessServiceImpl serviceImpl, int cpuCount, long cpuFeatures);
 
     /**
      * Force the child process to exit.
      */
     private static native void nativeExitChildProcess();
 
     private native void nativeShutdownMainThread();
 }