headless: Allow protocol handler customization

headless/public/headless_browser.h

Index: headless/public/headless_browser.h
diff --git a/headless/public/headless_browser.h b/headless/public/headless_browser.h
index 4b360575148edfe0ba214270d6921990ce3d9ffe..c1f5b4d0974d9bf7d7ca58c63ef9fb34b7695f33 100644
--- a/headless/public/headless_browser.h
+++ b/headless/public/headless_browser.h
@@ -7,6 +7,7 @@
 
 #include <memory>
 #include <string>
+#include <unordered_map>
 
 #include "base/callback.h"
 #include "base/macros.h"
@@ -14,6 +15,7 @@
 #include "headless/public/headless_export.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/ip_endpoint.h"
+#include "net/url_request/url_request_job_factory.h"
 
 namespace base {
 class MessagePump;
@@ -61,6 +63,10 @@ class HEADLESS_EXPORT HeadlessBrowser {
   DISALLOW_COPY_AND_ASSIGN(HeadlessBrowser);
 };
 
+using ProtocolHandlerMap = std::unordered_map<
+    std::string,
+    std::unique_ptr<net::URLRequestJobFactory::ProtocolHandler>>;
+
 // Embedding API overrides for the headless browser.
 struct HeadlessBrowser::Options {
   class Builder;
@@ -97,6 +103,10 @@ struct HeadlessBrowser::Options {
   // web content, which can be a security risk.
   bool single_process_mode;
 
+  // Custom network protocol handlers. These can be used to override URL
+  // fetching for different network schemes.
+  ProtocolHandlerMap protocol_handlers;
+
  private:
   Options(int argc, const char** argv);
 
@@ -115,6 +125,7 @@ class HeadlessBrowser::Options::Builder {
   Builder& SetProxyServer(const net::HostPortPair& proxy_server);
   Builder& SetHostResolverRules(const std::string& host_resolver_rules);
   Builder& SetSingleProcessMode(bool single_process_mode);
+  Builder& SetProtocolHandlers(ProtocolHandlerMap protocol_handlers);
 
   Options Build();