Add a fuzzer for HttpProxyClientSocket.

net/BUILD.gn

Index: net/BUILD.gn
diff --git a/net/BUILD.gn b/net/BUILD.gn
index b982b128ea055628de5b2b02af0f5f15a9f72f86..48b6db3f9942832ba60f21f339afb51931905f68 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -1972,6 +1972,19 @@ fuzzer_test("net_http_chunked_decoder_fuzzer") {
   dict = "http/http_chunked_decoder_fuzzer.dict"
 }
 
+fuzzer_test("net_http_proxy_client_socket_fuzzer") {
+  sources = [
+    "http/http_proxy_client_socket_fuzzer.cc",
+  ]
+  deps = [
+    ":net_fuzzer_test_support",
+    ":test_support",
+    "//base",
+    "//net",
+  ]
+  dict = "http/http_chunked_decoder_fuzzer.dict"

[eroman, 2016/04/15 19:07:21]

do you think the problem is it isn't being used when run locally, or the
construct here is broken?

[mmenke, 2016/04/15 19:23:52]

Oops, thought I removed this.

I think it's broken, or I'm not making a dictionary correctly.  I filed a bug
against it - https://crbug.com/603964

Even if not broken, I'm not going to land something I can't/haven't run
successfully locally, and without running it through a try job.

+}
+
 fuzzer_test("net_quic_crypto_framer_parse_message_fuzzer") {
   sources = [
     "quic/quic_crypto_framer_parse_message_fuzzer.cc",