Support C and Objective-C in jumbo base scripts.

build/config/jumbo.gni

Index: build/config/jumbo.gni
diff --git a/build/config/jumbo.gni b/build/config/jumbo.gni
index baf19f1b6bf91c39a5a3c25aded68027de6485cc..4a5f22f4a94ee0d2937adbe6ef5088857679df44 100644
--- a/build/config/jumbo.gni
+++ b/build/config/jumbo.gni
@@ -86,6 +86,23 @@ template("jumbo_target") {
       current_file_index += 1
     }
 
+    has_objective_c_file = false
+    has_c_file = false
+    foreach(source_file, invoker.sources) {
+      source_ext = get_path_info(source_file, "extension")
+      if (source_ext == "c") {
+        has_c_file = true
+      } else if (source_ext == "mm") {
+        has_objective_c_file = true
+      }
+    }
+    if (has_c_file) {
+      jumbo_files += [ "$gen_target_dir/" + target_name + "_jumbo_c.c" ]
+    }
+    if (has_objective_c_file) {
+      jumbo_files += [ "$gen_target_dir/" + target_name + "_jumbo_mm.mm" ]
+    }
+
     merge_action_name = target_name + "__jumbo_merge"
 
     # Create an action that calls a script that merges all the source files.
@@ -125,11 +142,9 @@ template("jumbo_target") {
       sources = jumbo_files + excluded_sources
 
       # Need to keep the headers in sources so that dependency checks
-      # work, and we need to keep Objective-C code since they
-      # cannot be merged into a cc file (FIXME).
+      # work.
       foreach(source_file, invoker.sources) {
-        source_ext = get_path_info(source_file, "extension")
-        if (source_ext == "h" || source_ext == "mm") {
+        if (get_path_info(source_file, "extension") == "h") {
           sources += [ source_file ]
         }
       }