Add support for GCM subtypes to desktop Instance ID implementation

google_apis/gcm/engine/registration_request.cc

Index: google_apis/gcm/engine/registration_request.cc
diff --git a/google_apis/gcm/engine/registration_request.cc b/google_apis/gcm/engine/registration_request.cc
index 287732a76803e1d4f50398a3a8b6d0310e1f6c18..79076b83434c2489ae7d021aacaeb78ba119584a 100644
--- a/google_apis/gcm/engine/registration_request.cc
+++ b/google_apis/gcm/engine/registration_request.cc
@@ -33,7 +33,8 @@ const char kRegistrationRequestContentType[] =
     "application/x-www-form-urlencoded";
 
 // Request constants.
-const char kAppIdKey[] = "app";
+const char kCategoryKey[] = "app";
+const char kSubtypeKey[] = "X-subtype";
 const char kDeviceIdKey[] = "device";
 const char kLoginHeader[] = "AidLogin";
 
@@ -73,10 +74,17 @@ bool ShouldRetryWithStatus(RegistrationRequest::Status status) {
 
 }  // namespace
 
-RegistrationRequest::RequestInfo::RequestInfo(uint64_t android_id,
-                                              uint64_t security_token,
-                                              const std::string& app_id)
-    : android_id(android_id), security_token(security_token), app_id(app_id) {
+RegistrationRequest::RequestInfo::RequestInfo(
+    uint64_t android_id,
+    uint64_t security_token,
+    const std::string& app_id,
+    bool use_subtype,
+    const std::string& category_for_subtypes)
+    : android_id(android_id),
+      security_token(security_token),
+      app_id(app_id),
+      use_subtype(use_subtype),
+      category_for_subtypes(category_for_subtypes) {
   DCHECK(android_id != 0UL);
   DCHECK(security_token != 0UL);
 }
@@ -148,7 +156,13 @@ void RegistrationRequest::BuildRequestHeaders(std::string* extra_headers) {
 }
 
 void RegistrationRequest::BuildRequestBody(std::string* body) {
-  BuildFormEncoding(kAppIdKey, request_info_.app_id, body);
+  if (request_info_.use_subtype) {
+    BuildFormEncoding(kCategoryKey, request_info_.category_for_subtypes, body);
+    BuildFormEncoding(kSubtypeKey, request_info_.app_id, body);
+  } else {
+    BuildFormEncoding(kCategoryKey, request_info_.app_id, body);
+  }
+
   BuildFormEncoding(kDeviceIdKey,
                     base::Uint64ToString(request_info_.android_id),
                     body);