Add clang-format config file.

.clang-format

@@ -0,0 +1,35 @@
+# Defines the Chromium style for automatic reformatting.
+# http://clang.llvm.org/docs/ClangFormatStyleOptions.html
+BasedOnStyle: Chromium
+# This defaults to 'Auto'. Explicitly set it for a while, so that
+# 'vector<vector<int> >' in existing files gets formatted to
+# 'vector<vector<int>>'. ('Auto' means that clang-format will only use
+# 'int>>' if the file already contains at least one such instance.)
+Standard: Cpp11
+# Make sure code like:
+# IPC_BEGIN_MESSAGE_MAP()
+#   IPC_MESSAGE_HANDLER(WidgetHostViewHost_Update, OnUpdate)
+# IPC_END_MESSAGE_MAP()
+# gets correctly indented.
+MacroBlockBegin: "^\
+BEGIN_MSG_MAP|\
+BEGIN_MSG_MAP_EX|\
+BEGIN_SAFE_MSG_MAP_EX|\
+CR_BEGIN_MSG_MAP_EX|\
+IPC_BEGIN_MESSAGE_MAP|\
+IPC_BEGIN_MESSAGE_MAP_WITH_PARAM|\
+IPC_PROTOBUF_MESSAGE_TRAITS_BEGIN|\
+IPC_STRUCT_BEGIN|\
+IPC_STRUCT_BEGIN_WITH_PARENT|\
+IPC_STRUCT_TRAITS_BEGIN|\
+POLPARAMS_BEGIN|\
+PPAPI_BEGIN_MESSAGE_MAP$"
+MacroBlockEnd: "^\
+CR_END_MSG_MAP|\
+END_MSG_MAP|\
+IPC_END_MESSAGE_MAP|\
+IPC_PROTOBUF_MESSAGE_TRAITS_END|\
+IPC_STRUCT_END|\
+IPC_STRUCT_TRAITS_END|\
+POLPARAMS_END|\
+PPAPI_END_MESSAGE_MAP$"