Fix some net/spdy lint picks, from git cl lint.

net/spdy/spdy_write_queue_unittest.cc

Index: net/spdy/spdy_write_queue_unittest.cc
diff --git a/net/spdy/spdy_write_queue_unittest.cc b/net/spdy/spdy_write_queue_unittest.cc
index 87f7d8b82bb3131617b21c83d8e9760dfada84dd..53f52f113f5aa449fdc7b7563b2558291e2c3da3 100644
--- a/net/spdy/spdy_write_queue_unittest.cc
+++ b/net/spdy/spdy_write_queue_unittest.cc
@@ -50,7 +50,7 @@ std::unique_ptr<SpdyBufferProducer> IntToProducer(int i) {
 // SpdyWriteQueue upon destruction.
 class RequeingBufferProducer : public SpdyBufferProducer {
  public:
-  RequeingBufferProducer(SpdyWriteQueue* queue) {
+  explicit RequeingBufferProducer(SpdyWriteQueue* queue) {
     buffer_.reset(new SpdyBuffer(kOriginal, arraysize(kOriginal)));
     buffer_->AddConsumeCallback(
         base::Bind(RequeingBufferProducer::ConsumeCallback, queue));