Fix gRPC build failure on Android with Clang.

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")
@@ skipping 69 matching lines @@
     wanted_libs = ("gpr", "grpc", "grpc_unsecure", "grpc++", "grpc++_unsecure",
                    "grpc_cronet", "grpc_plugin_support")
     return lib.build in ("all", "protoc") and lib.get("name", "") in wanted_libs
 
   def wanted_binary(tgt):
     wanted_binaries = ("grpc_cpp_plugin",)
     return tgt.build == "protoc" and tgt.get("name", "") in wanted_binaries
 
   def only_on_host_toolchain(tgt):
     return tgt.get("name", "") in ("grpc_plugin_support", "grpc_cpp_plugin")
+
+  def contains_wrap_memcpy(srcs):
+    for src in srcs:
+      if 'wrap_memcpy' in src:
+        return True
+    return False
+
+  def get_wrap_memcpy(srcs):
+    return [s for s in srcs if "wrap_memcpy" in s]
   %>
 
   % for lib in libs:
   % if wanted_lib(lib):
   % if only_on_host_toolchain(lib):
   # Only compile the plugin for the host architecture.
   if (current_toolchain == host_toolchain) {
   ${cc_library(lib)}
   }
   % else:
@@ skipping 27 matching lines @@
   % for hdr in lib.get("public_headers", []):
       "${hdr}",
   % endfor
   % for hdr in hdrs:
       "${hdr}",
   % endfor
   % for src in srcs:
       "${src}",
   % endfor
     ]
+  % if contains_wrap_memcpy(srcs):
+    if (is_android) {
+      # gRPC memcpy wrapping logic isn't Android-friendly.
+      # See https://crbug.com/661171
+      sources -= [
+  % for src in get_wrap_memcpy(srcs):
+        "${src}",
+  % endfor
+      ]
+    }
+  % endif
     deps = [
   % for dep in get_deps(lib):
       "${dep}",
   % endfor
     ]
     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [
       "//build/config/compiler:no_chromium_code",
   % for config in get_extra_configs(lib):
       "${config}",
@@ skipping 20 matching lines @@
     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [
       "//build/config/compiler:no_chromium_code",
   % for config in get_extra_configs(tgt):
       "${config}",
   % endfor
     ]
     public_configs = [ ":grpc_config" ]
   }
   </%def>