Selectively perform JNI registration in render processes on Android.

base/android/java/src/org/chromium/base/EarlyTraceEvent.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.base;
 
 import android.os.Process;
 import android.os.StrictMode;
 import android.os.SystemClock;
 
 import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
 import org.chromium.base.annotations.SuppressFBWarnings;
 
 import java.io.File;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 /** Support for early tracing, before the native library is loaded.
  *
  * This is limited, as:
  * - Arguments are not supported
  * - Thread time is not reported
  * - Two events with the same name cannot be in progress at the same time.
  *
  * Events recorded here are buffered in Java until the native library is available. Then it waits
  * for the completion of pending events, and sends the events to the native side.
  *
  * Locking: This class is threadsafe. It is enabled when general tracing is, and then disabled when
  *          tracing is enabled from the native side. Event completions are still processed as long
  *          as some are pending, then early tracing is permanently disabled after dumping the
  *          events.  This means that if any early event is still pending when tracing is disabled,
  *          all early events are dropped.
  */
 @JNINamespace("base::android")
+@MainDex
 public class EarlyTraceEvent {
     // Must be kept in sync with the native kAndroidTraceConfigFile.
     private static final String TRACE_CONFIG_FILENAME = "/data/local/chrome-trace-config.json";
 
     /** Single trace event. */
     @VisibleForTesting
     static final class Event {
         final String mName;
         final int mThreadId;
         final long mBeginTimeMs;
@@ skipping 122 matching lines @@
         long offsetMs = (nativeNowUs - javaNowUs) / 1000;
         for (Event event : events) {
             nativeRecordEarlyEvent(event.mName, event.mBeginTimeMs + offsetMs,
                     event.mEndTimeMs + offsetMs, event.mThreadId);
         }
     }
 
     private static native void nativeRecordEarlyEvent(
             String name, long beginTimeMs, long endTimeMs, int threadId);
 }