Reland of Android Logging.java: Load native library only when needed (patchset #1 id:1 of https://codereview.webrtc.org/2816753002/ )

Reason for revert:
Fix bug in original CL.

Original issue's description:
> Revert of Android Logging.java: Load native library only when needed (patchset #3 id:40001 of https://codereview.webrtc.org/2803203002/ )
>
> Reason for revert:
> Breaks C++ logs in Java apps.
>
> Original issue's description:
> > Android Logging.java: Load native library only when needed
> >
> > Logging.java currently always tries to load jingle_peerconnection_so in
> > the static section, but some clients don't want to use it. This CL loads
> > jingle_peerconnection_so only when a client requests it by calling one
> > of:
> >  * Logging.enableLogThreads
> >  * Logging.enableLogTimeStamps
> >  * Logging.enableTracing
> >  * Logging.enableLogToDebugOutput
> >
> > BUG=b/36410678
> >
> > Review-Url: https://codereview.webrtc.org/2803203002
> > Cr-Commit-Position: refs/heads/master@{#17647}
> > Committed: dee5eb14e1
>
> TBR=sakal@webrtc.org,glaznev@webrtc.org,noahric@chromium.org,magjed@webrtc.org
> # Not skipping CQ checks because original CL landed more than 1 days ago.
> BUG=b/36410678
>
> Review-Url: https://codereview.webrtc.org/2816753002
> Cr-Commit-Position: refs/heads/master@{#17676}
> Committed: 6e4a4427dc

TBR=sakal@webrtc.org,glaznev@webrtc.org,noahric@chromium.org,brandtr@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=b/36410678

Review-Url: https://codereview.webrtc.org/2817593003
Cr-Commit-Position: refs/heads/master@{#17677}

webrtc/base/java/src/org/webrtc/Logging.java

@@ -16,24 +16,41 @@ import java.util.EnumSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-/** Java wrapper for WebRTC logging. */
+/**
+ * Java wrapper for WebRTC logging. Logging defaults to java.util.logging.Logger, but will switch to
+ * native logging (rtc::LogMessage) if one of the following static functions are called from the
+ * app:
+ * - Logging.enableLogThreads
+ * - Logging.enableLogTimeStamps
+ * - Logging.enableTracing
+ * - Logging.enableLogToDebugOutput
+ * Using native logging requires the presence of the jingle_peerconnection_so library.
+ */
 public class Logging {
-  private static final Logger fallbackLogger = Logger.getLogger("org.webrtc.Logging");
+  private static final Logger fallbackLogger = createFallbackLogger();
   private static volatile boolean tracingEnabled;
   private static volatile boolean loggingEnabled;
-  private static volatile boolean nativeLibLoaded;
+  private static enum NativeLibStatus { UNINITIALIZED, LOADED, FAILED }
+  private static volatile NativeLibStatus nativeLibStatus = UNINITIALIZED;
 
-  static {
+  private static Logger createFallbackLogger() {
+    final Logger fallbackLogger = Logger.getLogger("org.webrtc.Logging");
+    fallbackLogger.setLevel(Level.ALL);
+    return fallbackLogger;
+  }
+
+  private static boolean loadNativeLibrary() {
+    if (nativeLibStatus == NativeLibStatus.UNINITIALIZED) {
       try {
         System.loadLibrary("jingle_peerconnection_so");
-      nativeLibLoaded = true;
+        nativeLibStatus = NativeLibStatus.LOADED;
       } catch (UnsatisfiedLinkError t) {
-      // If native logging is unavailable, log to system log.
-      fallbackLogger.setLevel(Level.ALL);
-
+        nativeLibStatus = NativeLibStatus.FAILED;
         fallbackLogger.log(Level.WARNING, "Failed to load jingle_peerconnection_so: ", t);
       }
     }
+    return nativeLibStatus == NativeLibStatus.LOADED;
+  }
 
   // Keep in sync with webrtc/common_types.h:TraceLevel.
   public enum TraceLevel {
@@ -63,7 +80,7 @@ public class Logging {
   public enum Severity { LS_SENSITIVE, LS_VERBOSE, LS_INFO, LS_WARNING, LS_ERROR, LS_NONE }
 
   public static void enableLogThreads() {
-    if (!nativeLibLoaded) {
+    if (!loadNativeLibrary()) {
       fallbackLogger.log(Level.WARNING, "Cannot enable log thread because native lib not loaded.");
       return;
     }
@@ -71,7 +88,7 @@ public class Logging {
   }
 
   public static void enableLogTimeStamps() {
-    if (!nativeLibLoaded) {
+    if (!loadNativeLibrary()) {
       fallbackLogger.log(
           Level.WARNING, "Cannot enable log timestamps because native lib not loaded.");
       return;
@@ -83,7 +100,7 @@ public class Logging {
   // On Android, use "logcat:" for |path| to send output there.
   // Note: this function controls the output of the WEBRTC_TRACE() macros.
   public static synchronized void enableTracing(String path, EnumSet<TraceLevel> levels) {
-    if (!nativeLibLoaded) {
+    if (!loadNativeLibrary()) {
       fallbackLogger.log(Level.WARNING, "Cannot enable tracing because native lib not loaded.");
       return;
     }
@@ -103,7 +120,7 @@ public class Logging {
   // output. On Android, the output will be directed to Logcat.
   // Note: this function starts collecting the output of the LOG() macros.
   public static synchronized void enableLogToDebugOutput(Severity severity) {
-    if (!nativeLibLoaded) {
+    if (!loadNativeLibrary()) {
       fallbackLogger.log(Level.WARNING, "Cannot enable logging because native lib not loaded.");
       return;
     }

webrtc/sdk/android/api/org/webrtc/FileVideoCapturer.java

@@ -20,6 +20,10 @@ import java.io.RandomAccessFile;
 import java.io.IOException;
 
 public class FileVideoCapturer implements VideoCapturer {
+  static {
+    System.loadLibrary("jingle_peerconnection_so");
+  }
+
   private interface VideoReader {
     int getFrameWidth();
     int getFrameHeight();

webrtc/sdk/android/api/org/webrtc/VideoFileRenderer.java

@@ -22,6 +22,10 @@ import java.util.ArrayList;
  * Can be used to save the video frames to file.
  */
 public class VideoFileRenderer implements VideoRenderer.Callbacks {
+  static {
+    System.loadLibrary("jingle_peerconnection_so");
+  }
+
   private static final String TAG = "VideoFileRenderer";
 
   private final HandlerThread renderThread;