Implement Drain() on HttpPipelinedStream.

net/http/http_response_body_drainer_unittest.cc

Index: net/http/http_response_body_drainer_unittest.cc
diff --git a/net/http/http_response_body_drainer_unittest.cc b/net/http/http_response_body_drainer_unittest.cc
index f580f94617cf6d9d1fb00184d07d57506a4be9d9..7568944c9c9693162fe328f4078b3af729a1b4c0 100644
--- a/net/http/http_response_body_drainer_unittest.cc
+++ b/net/http/http_response_body_drainer_unittest.cc
@@ -255,6 +255,24 @@ TEST_F(HttpResponseBodyDrainerTest, DrainBodyTooLarge) {
   EXPECT_TRUE(result_waiter_.WaitForResult());
 }
 
+TEST_F(HttpResponseBodyDrainerTest, StartBodyTooLarge) {
+  TestOldCompletionCallback callback;
+  int too_many_chunks =
+      HttpResponseBodyDrainer::kDrainBodyBufferSize / kMagicChunkSize;
+  too_many_chunks += 1;  // Now it's too large.
+
+  mock_stream_->set_num_chunks(0);
+  drainer_->StartWithSize(session_, too_many_chunks * kMagicChunkSize);
+  EXPECT_TRUE(result_waiter_.WaitForResult());
+}
+
+TEST_F(HttpResponseBodyDrainerTest, StartWithNothingToDo) {
+  TestOldCompletionCallback callback;
+  mock_stream_->set_num_chunks(0);
+  drainer_->StartWithSize(session_, 0);
+  EXPECT_FALSE(result_waiter_.WaitForResult());
+}
+
 }  // namespace
 
 }  // namespace net