Flush control frames; don't flush user frames.

okhttp-protocols/src/main/java/com/squareup/okhttp/internal/spdy/Http20Draft09.java

@@ -317,6 +317,7 @@ public final class Http20Draft09 implements Variant {
     @Override public synchronized void connectionHeader() throws IOException {
       if (!client) return; // Nothing to write; servers don't send connection headers!
       out.write(CONNECTION_HEADER);
+      out.flush();
     }
 
     @Override
@@ -409,6 +410,7 @@ public final class Http20Draft09 implements Variant {
         out.writeInt(i & 0xffffff);
         out.writeInt(settings.get(i));
       }
+      out.flush();
     }
 
     @Override public synchronized void ping(boolean ack, int payload1, int payload2)
@@ -420,6 +422,7 @@ public final class Http20Draft09 implements Variant {
       frameHeader(length, type, flags, streamId);
       out.writeInt(payload1);
       out.writeInt(payload2);
+      out.flush();
     }
 
     @Override
@@ -436,6 +439,7 @@ public final class Http20Draft09 implements Variant {
       if (debugData.length > 0) {
         out.write(debugData);
       }
+      out.flush();
     }
 
     @Override public synchronized void windowUpdate(int streamId, long windowSizeIncrement)
@@ -449,6 +453,7 @@ public final class Http20Draft09 implements Variant {
       byte flags = FLAG_NONE;
       frameHeader(length, type, flags, streamId);
       out.writeInt((int) windowSizeIncrement);
+      out.flush();
     }
 
     @Override public void close() throws IOException {

okhttp-protocols/src/main/java/com/squareup/okhttp/internal/spdy/Spdy3.java

@@ -369,7 +369,6 @@ final class Spdy3 implements Variant {
       out.writeInt((flags & 0xff) << 24 | length & 0xffffff);
       out.writeInt(streamId & 0x7fffffff);
       headerBlockBuffer.writeTo(out);
-      out.flush();
     }
 
     @Override public synchronized void rstStream(int streamId, ErrorCode errorCode)