Moving gRPC support interfaces out of cronet and into a new component.

build/config/ios/rules.gni

Index: build/config/ios/rules.gni
diff --git a/build/config/ios/rules.gni b/build/config/ios/rules.gni
index 93565f065b2b5a92626395dac3ce8fc640bebb48..5e9b1e9f0e402eda49fdc1cb55cabbdaf319bf38 100644
--- a/build/config/ios/rules.gni
+++ b/build/config/ios/rules.gni
@@ -1004,6 +1004,13 @@ template("ios_framework_bundle") {
           _header_map_filename,
         ]
 
+        forward_variables_from(invoker,
+                               [
+                                 "deps",
+                                 "public_deps",
+                                 "testonly",
+                               ])
+
         # The header map generation only wants the list of headers, not all of
         # sources, so filter any non-header source files from "sources". It is
         # less error prone that having the developer duplicate the list of all
@@ -1018,6 +1025,11 @@ template("ios_framework_bundle") {
         sources = invoker.sources
         set_sources_assignment_filter([])
 
+        # Add public_headers in case any of these files included in sources.
+        if (defined(invoker.public_headers)) {
+          sources += invoker.public_headers
+        }
+
         args = [
                  rebase_path(_header_map_filename),
                  rebase_path(_framework_root, root_build_dir),
@@ -1041,6 +1053,12 @@ template("ios_framework_bundle") {
         outputs = [
           "$_framework_root/Headers/{{source_file_part}}",
         ]
+        forward_variables_from(invoker,
+                               [
+                                 "deps",
+                                 "public_deps",
+                                 "testonly",
+                               ])
       }
 
       config(_headers_map_config) {
@@ -1054,6 +1072,7 @@ template("ios_framework_bundle") {
           ":$_copy_public_headers_target",
           ":$_create_module_map_target",
         ]
+        forward_variables_from(invoker, [ "testonly" ])
       }
 
       config(_framework_headers_config) {