Use longer delay when batch processing incoming messages.

// FREEBIE

SignalServiceKit/src/Messages/OWSBatchMessageProcessor.m

@@ -317,6 +317,9 @@ NSString *const OWSMessageContentJobFinderExtensionGroup = @"OWSMessageContentJo
 {
     AssertOnDispatchQueue(self.serialQueue);
 
+    // We want a value that is just high enough to yield perf benefits.
+    const NSUInteger kIncomingMessageBatchSize = 16;
+
     NSArray<OWSMessageContentJob *> *jobs = [self.finder nextJobsForBatchSize:kIncomingMessageBatchSize];
     OWSAssert(jobs);
     if (jobs.count < 1) {

SignalServiceKit/src/Messages/OWSMessageHandler.h

@@ -4,8 +4,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-extern const NSUInteger kIncomingMessageBatchSize;
-
 @class OWSSignalServiceProtosContent;
 @class OWSSignalServiceProtosDataMessage;
 @class OWSSignalServiceProtosEnvelope;

SignalServiceKit/src/Messages/OWSMessageHandler.m

@@ -7,15 +7,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-// We need to use a consistent batch size throughout
-// the incoming message pipeline (i.e. in the
-// "decrypt" and "process" steps), or the pipeline
-// doesn't flow smoothly.
-//
-// We want a value that is just high enough to yield
-// perf benefits.  The right value is probably 5-15.
-const NSUInteger kIncomingMessageBatchSize = 10;
-
 // used in log formatting
 NSString *envelopeAddress(OWSSignalServiceProtosEnvelope *envelope)
 {