Added a net::BidirectionalStream to expose a bidirectional streaming interface

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index b81acbe25aecc1db418a72e93bbbc55600b81629..f1749f4dec7f4c0154a893d93f189f027c0ede83 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -597,6 +597,9 @@
       # Enables used resource whitelist generation; disabled by default.
       'enable_resource_whitelist_generation%': 0,
 
+      # Enables BidrectionalSteam; disabled by default.
+      'enable_bidirectional_stream': 0,

[mef, 2015/12/17 22:42:09]

do we need to explicitly enable it in cronet?

[xunjieli, 2015/12/18 15:15:23]

In Cronet, we can use the preprocessor define ENABLE_BIDIRECTIONAL_STREAM. But
yes, we will need a follow-up CL to enable this when running net_unittests on
Cronet bots.

[mef, 2015/12/18 15:45:03]

Hrm, just setting the define ENABLE_BIDIRECTIONAL_STREAM on Cronet project won't
help, but it shouldn't be a problem to set in cr_cronet.py and on bots.

[xunjieli, 2015/12/18 15:59:29]

Ah, yes, you are right! The ENABLE_BIDIRECTIONAL_STREAM needs to be set when
compiling net/, so we either need a custom net target, or use the variable when
running gyp. We probably also need to have a custom Cronet build too for this
purpose. I don't imagine cronet customers of the UrlRequest interface is
interested in the BidirectionalStream support. 

+
       # Enable FILE support by default.
       'disable_file_support%': 0,
 
@@ -1220,6 +1223,7 @@
     'enable_captive_portal_detection%': '<(enable_captive_portal_detection)',
     'disable_file_support%': '<(disable_file_support)',
     'disable_ftp_support%': '<(disable_ftp_support)',
+    'enable_bidirectional_stream%': '<(enable_bidirectional_stream)',
     'enable_task_manager%': '<(enable_task_manager)',
     'sas_dll_path%': '<(sas_dll_path)',
     'wix_path%': '<(wix_path)',