Added Network Quality Estimator Real-time interface to Cronet

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

Index: components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
diff --git a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
index 7bae2883221d5340a4ddbb23c19c9bf4865d978a..0988e9e163a554a232857ecaf68b3b30629418f4 100644
--- a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
+++ b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java
@@ -12,6 +12,7 @@ import android.os.Looper;
 import android.os.Process;
 import android.util.Log;
 
+import org.chromium.base.ObserverList;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
@@ -42,6 +43,11 @@ class CronetUrlRequestContext extends UrlRequestContext {
     private long mUrlRequestContextAdapter = 0;
     private Thread mNetworkThread;
 
+    private final ObserverList<NetworkQualityRTTObserver> mRTTObserverList =
+            new ObserverList<NetworkQualityRTTObserver>();
+    private final ObserverList<NetworkQualityThroughputObserver> mThroughputObserverList =
+            new ObserverList<NetworkQualityThroughputObserver>();
+
     @UsedByReflection("UrlRequestContext.java")
     public CronetUrlRequestContext(Context context,
                                    UrlRequestContextConfig config) {
@@ -148,6 +154,60 @@ class CronetUrlRequestContext extends UrlRequestContext {
         }
     }
 
+    @Override
+    public void enableNetworkQualityEstimator(
+            boolean useLocalHostRequests, boolean useSmallerResponses) {
+        synchronized (mLock) {
+            checkHaveAdapter();
+            nativeEnableNetworkQualityEstimator(
+                    mUrlRequestContextAdapter, useLocalHostRequests, useSmallerResponses);
+        }
+    }
+
+    @Override
+    public void addRTTObserver(NetworkQualityRTTObserver observer) {
+        if (mRTTObserverList.isEmpty()) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+                nativeProvideRTTObservations(mUrlRequestContextAdapter, true);
+            }
+        }
+        mRTTObserverList.addObserver(observer);
+    }
+
+    @Override
+    public void removeRTTObserver(NetworkQualityRTTObserver observer) {
+        mRTTObserverList.removeObserver(observer);
+        if (mRTTObserverList.isEmpty()) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+                nativeProvideRTTObservations(mUrlRequestContextAdapter, false);
+            }
+        }
+    }
+
+    @Override
+    public void addThroughputObserver(NetworkQualityThroughputObserver observer) {
+        if (mThroughputObserverList.isEmpty()) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+                nativeProvideThroughputObservations(mUrlRequestContextAdapter, true);
+            }
+        }
+        mThroughputObserverList.addObserver(observer);
+    }
+
+    @Override
+    public void removeThroughputObserver(NetworkQualityThroughputObserver observer) {
+        mThroughputObserverList.removeObserver(observer);

[mef, 2015/08/28 20:53:16]

this happens on arbitrary thread.

[bengr, 2015/08/28 23:51:36]

Are you saying that mThroughputObserverList isn't thread safe? If so, do you
have any recommendations? Do you enforce use on a particular thread or
something?

+        if (mThroughputObserverList.isEmpty()) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+                nativeProvideThroughputObservations(mUrlRequestContextAdapter, false);
+            }
+        }
+    }
+
     /**
      * Mark request as started to prevent shutdown when there are active
      * requests.
@@ -209,6 +269,22 @@ class CronetUrlRequestContext extends UrlRequestContext {
         Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
     }
 
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onRTTObservation(int value, int when, int source) {
+        for (NetworkQualityRTTObserver observer : mRTTObserverList) {

[mef, 2015/08/28 20:53:16]

this happens on network thread. 
If anything, the iteration should be done under lock, but I wonder whether we
should actually post observations to some executor, so if the app does anything
interesting, like write observation to disk, it would not block the network
thread.

[bengr, 2015/08/28 23:51:36]

Good idea. Do you have examples of where you use an executor? I can do that in a
follow-up CL.

+            observer.onRTTObservation(value, when, source);
+        }
+    }
+
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onThroughputObservation(int value, int when, int source) {
+        for (NetworkQualityThroughputObserver observer : mThroughputObserverList) {
+            observer.onThroughputObservation(value, when, source);
+        }
+    }
+
     // Native methods are implemented in cronet_url_request_context.cc.
     private static native long nativeCreateRequestContextAdapter(String config);
 
@@ -226,4 +302,14 @@ class CronetUrlRequestContext extends UrlRequestContext {
 
     @NativeClassQualifiedName("CronetURLRequestContextAdapter")
     private native void nativeInitRequestContextOnMainThread(long nativePtr);
+
+    @NativeClassQualifiedName("CronetURLRequestContextAdapter")
+    private native void nativeEnableNetworkQualityEstimator(
+            long nativePtr, boolean useLocalHostRequests, boolean useSmallerResponses);
+
+    @NativeClassQualifiedName("CronetURLRequestContextAdapter")
+    private native void nativeProvideRTTObservations(long nativePtr, boolean should);
+
+    @NativeClassQualifiedName("CronetURLRequestContextAdapter")
+    private native void nativeProvideThroughputObservations(long nativePtr, boolean should);
 }