Update //base to chromium 9659b08ea5a34f889dc4166217f438095ddc10d2

base/android/java/src/org/chromium/base/TraceEvent.java

 // Copyright 2014 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.Looper;
 import android.os.MessageQueue;
 import android.os.SystemClock;
 import android.util.Log;
 import android.util.Printer;
 /**
  * Java mirror of Chrome trace event API. See base/trace_event/trace_event.h. Unlike the native
  * version, Java does not have stack objects, so a TRACE_EVENT() which does both TRACE_EVENT_BEGIN()
  * and TRACE_EVENT_END() in ctor/dtor is not possible.
  * It is OK to use tracing before the native library has loaded, but such traces will
  * be ignored. (Perhaps we could devise to buffer them up in future?).
  */
 @JNINamespace("base::android")
 public class TraceEvent {
 
     private static volatile boolean sEnabled = false;
+    private static volatile boolean sATraceEnabled = false; // True when taking an Android systrace.
 
     private static class BasicLooperMonitor implements Printer {
         @Override
         public void println(final String line) {
             if (line.startsWith(">")) {
                 beginHandling(line);
             } else {
                 assert line.startsWith("<");
                 endHandling(line);
             }
@@ skipping 136 matching lines @@
     public static void registerNativeEnabledObserver() {
         nativeRegisterEnabledObserver();
     }
 
     /**
      * Notification from native that tracing is enabled/disabled.
      */
     @CalledByNative
     public static void setEnabled(boolean enabled) {
         sEnabled = enabled;
+        // Android M+ systrace logs this on its own. Only log it if not writing to Android systrace.
+        if (sATraceEnabled) return;
         ThreadUtils.getUiThreadLooper().setMessageLogging(
                 enabled ? LooperMonitorHolder.sInstance : null);
     }
 
     /**
      * Enables or disabled Android systrace path of Chrome tracing. If enabled, all Chrome
      * traces will be also output to Android systrace. Because of the overhead of Android
      * systrace, this is for WebView only.
      */
     public static void setATraceEnabled(boolean enabled) {
-        if (sEnabled == enabled) return;
+        if (sATraceEnabled == enabled) return;
+        sATraceEnabled = enabled;
         if (enabled) {
+            // Calls TraceEvent.setEnabled(true) via
+            // TraceLog::EnabledStateObserver::OnTraceLogEnabled
             nativeStartATrace();
         } else {
+            // Calls TraceEvent.setEnabled(false) via
+            // TraceLog::EnabledStateObserver::OnTraceLogDisabled
             nativeStopATrace();
         }
     }
 
     /**
      * @return True if tracing is enabled, false otherwise.
      * It is safe to call trace methods without checking if TraceEvent
      * is enabled.
      */
     public static boolean enabled() {
@@ skipping 73 matching lines @@
     private static native void nativeStartATrace();
     private static native void nativeStopATrace();
     private static native void nativeInstant(String name, String arg);
     private static native void nativeBegin(String name, String arg);
     private static native void nativeEnd(String name, String arg);
     private static native void nativeBeginToplevel();
     private static native void nativeEndToplevel();
     private static native void nativeStartAsync(String name, long id);
     private static native void nativeFinishAsync(String name, long id);
 }