Reland "Reland "Injectable logging""

This is a reland of 21219a0e43446701810236fb9fdd59be072c12df

The default implementation of OnLogMessage(msg, sev, tag) discarded
the tag, resulting in FileRotatingLogSink not receiving tags.

Since the revert the default implementation of
OnLogMessage(msg, sev, tag) has been updated to add the tag to the log
message. A more efficient implementation of it has also been added for
FileRotatingLogSink.

Unit tests are added for the default implementation and for Loggable
injection.

Original change's description:
> Reland "Injectable logging"
>
> Any injected loggable or NativeLogger would be deleted if PCFactory
> was reinitialized without calling setInjectableLogger. Now native
> logging is not implemented as a Loggable, so it will remain active
> unless a Loggable is injected.
>
> This is a reland of 59216ec4a4151b1ba5478c8f2b5c9f01f4683d7f
>
> Original change's description:
> > Injectable logging
> >
> > Allows passing a Loggable to PCFactory.initializationOptions, which
> > is then injected to Logging.java and logging.h. Future log messages
> > in both Java and native will then be passed to this Loggable.
> >
> > Bug: webrtc:9225
> > Change-Id: I2ff693380639448301a78a93dc11d3a0106f0967
> > Reviewed-on: https://webrtc-review.googlesource.com/73243
> > Commit-Queue: Paulina Hensman <phensman@webrtc.org>
> > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#23241}
>
> Bug: webrtc:9225
> Change-Id: I2fe3fbc8c323814284bb62e43fe1870bdab581ee
> TBR: kwiberg
> Reviewed-on: https://webrtc-review.googlesource.com/77140
> Commit-Queue: Paulina Hensman <phensman@webrtc.org>
> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#23310}

Bug: webrtc:9225
Change-Id: I67a5728fe772f0bedc9509713ed8b8ffdc31af81
TBR: kwiberg
Reviewed-on: https://webrtc-review.googlesource.com/80860
Commit-Queue: Paulina Hensman <phensman@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23711}

rtc_base/java/src/org/webrtc/Logging.java

@@ -15,21 +15,35 @@ import java.io.StringWriter;
 import java.util.EnumSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.Nullable;
+import org.webrtc.Loggable;
 
 /**
- * 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:
+ * Java wrapper for WebRTC logging. Logging defaults to java.util.logging.Logger, but a custom
+ * logger implementing the Loggable interface can be injected along with a Severity. All subsequent
+ * log messages will then be redirected to the injected Loggable, except those with a severity lower
+ * than the specified severity, which will be discarded.
+ *
+ * It is also possible to switch to native logging (rtc::LogMessage) if one of the following static
+ * functions are called from the app:
  * - Logging.enableLogThreads
  * - Logging.enableLogTimeStamps
  * - Logging.enableLogToDebugOutput
  *
- * Using these APIs requires that the native library is loaded, using
- * PeerConnectionFactory.initialize.
+ * The priority goes:
+ * 1. Injected loggable
+ * 2. Native logging
+ * 3. Fallback logging.
+ * Only one method will be used at a time.
+ *
+ * Injecting a Loggable or using any of the enable... methods requires that the native library is
+ * loaded, using PeerConnectionFactory.initialize.
  */
 public class Logging {
   private static final Logger fallbackLogger = createFallbackLogger();
   private static volatile boolean loggingEnabled;
+  @Nullable private static Loggable loggable;
+  private static Severity loggableSeverity;
 
   private static Logger createFallbackLogger() {
     final Logger fallbackLogger = Logger.getLogger("org.webrtc.Logging");
@@ -37,6 +51,17 @@ public class Logging {
     return fallbackLogger;
   }
 
+  static void injectLoggable(Loggable injectedLoggable, Severity severity) {
+    if (injectedLoggable != null) {
+      loggable = injectedLoggable;
+      loggableSeverity = severity;
+    }
+  }
+
+  static void deleteInjectedLoggable() {
+    loggable = null;
+  }
+
   // TODO(solenberg): Remove once dependent projects updated.
   @Deprecated
   public enum TraceLevel {
@@ -83,6 +108,11 @@ public class Logging {
   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized void enableLogToDebugOutput(Severity severity) {
+    if (loggable != null) {
+      throw new IllegalStateException(
+          "Logging to native debug output not supported while Loggable is injected. "
+          + "Delete the Loggable before calling this method.");
+    }
     nativeEnableLogToDebugOutput(severity.ordinal());
     loggingEnabled = true;
   }
@@ -91,6 +121,16 @@ public class Logging {
     if (tag == null || message == null) {
       throw new IllegalArgumentException("Logging tag or message may not be null.");
     }
+    if (loggable != null) {
+      // Filter log messages below loggableSeverity.
+      if (severity.ordinal() < loggableSeverity.ordinal()) {
+        return;
+      }
+      loggable.onLogMessage(message, severity, tag);
+      return;
+    }
+
+    // Try native logging if no loggable is injected.
     if (loggingEnabled) {
       nativeLog(severity.ordinal(), tag, message);
       return;