Fix Android build issues and gRPC LB policy

templates/BUILD.gn.template

 %YAML 1.2
 --- |
   # GRPC Chromium BUILD.gn file.
   # This file has been automatically generated from a template file.
   # Please look at the templates directory instead.
   # This file can be regenerated from the template by running
   # tools/buildgen/generate_projects.sh
+  if (is_android) {
+    import("//build/config/android/config.gni")
+    import("//build/config/android/rules.gni")
+  }
+  
   config("grpc_config") {
     include_dirs = [
       ".",
       "include/",
     ]
 
     defines = [
       "GRPC_USE_PROTO_LITE",
       # TODO(xyzzyz): the <condition_variable> header in libstdc++-4.6 we're using
       # in Chromium has a bug, which causes a compilation error on Clang.
       # Therefore, we need to make gRPC not use standard library threading
       # support.
       # https://crbug.com/593874
       "GRPC_CXX0X_NO_THREAD",
     ]
+    
+    cflags_c = [
+      "-std=c99"
+    ]
+    
+    if (is_android) {
+      libs = [ "log" ] # For __android_log_write
+    }  
   }
 
   <%!
   def get_deps(target_dict):
     deps = []
     if target_dict.get("secure", False):
       deps = [
         "//third_party/boringssl",
       ]
 
@@ skipping 121 matching lines @@
     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [
       "//build/config/compiler:no_chromium_code",
   % for config in get_extra_configs(tgt):
       "${config}",
   % endfor
     ]
     public_configs = [ ":grpc_config" ]
   }
   </%def>