[Cronet] Add ExperimentalCronetEngine.Builder.setThreadPriority() API

components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java

Index: components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
diff --git a/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java b/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
index b9488c41e7099230c9eb2bcc18c004f895e5fbd9..f4747a4197cea3f43b1de12d6350c9caa147fde1 100644
--- a/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
+++ b/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
@@ -70,7 +70,8 @@ public class CronetUrlRequestContext extends CronetEngineBase {
      */
     private Thread mNetworkThread;
 
-    private boolean mNetworkQualityEstimatorEnabled;
+    private final boolean mNetworkQualityEstimatorEnabled;
+    private final int mNetworkThreadPriority;
 
     /**
      * Locks operations on network quality listeners, because listener
@@ -148,6 +149,8 @@ public class CronetUrlRequestContext extends CronetEngineBase {
 
     @UsedByReflection("CronetEngine.java")
     public CronetUrlRequestContext(final CronetEngineBuilderImpl builder) {
+        mNetworkQualityEstimatorEnabled = builder.networkQualityEstimatorEnabled();
+        mNetworkThreadPriority = builder.threadPriority(Process.THREAD_PRIORITY_BACKGROUND);

[mef, 2017/05/15 17:20:11]

It is unclear why passing default priority as argument is better than just
specifying it as default in builder.

[pauljensen, 2017/05/15 19:03:25]

Because there are different defaults for different callers that share one
builder.

         CronetLibraryLoader.ensureInitialized(builder.getContext(), builder);
         nativeSetMinLogLevel(getLoggingLevel());
         synchronized (mLock) {
@@ -156,7 +159,6 @@ public class CronetUrlRequestContext extends CronetEngineBase {
             if (mUrlRequestContextAdapter == 0) {
                 throw new NullPointerException("Context Adapter creation failed.");
             }
-            mNetworkQualityEstimatorEnabled = builder.networkQualityEstimatorEnabled();
         }
 
         // Init native Chromium URLRequestContext on init thread.
@@ -574,7 +576,7 @@ public class CronetUrlRequestContext extends CronetEngineBase {
         mNetworkThread = Thread.currentThread();
         mInitCompleted.open();
         Thread.currentThread().setName("ChromiumNet");
-        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
+        Process.setThreadPriority(mNetworkThreadPriority);
     }
 
     @SuppressWarnings("unused")