third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/README.chromium

Index: third_party/protobuf/README.chromium
diff --git a/third_party/protobuf/README.chromium b/third_party/protobuf/README.chromium
index 8838fbc2715f88ba266247fb32e58147b04ad0a0..85b1822c15afe63c964afa23d4febd6bc6123cc0 100644
--- a/third_party/protobuf/README.chromium
+++ b/third_party/protobuf/README.chromium
@@ -3,14 +3,13 @@ Short Name: protobuf
 URL: https://github.com/google/protobuf
 License: BSD
 License File: LICENSE
-Version: 3.0.0-beta-3
-Revision: 3470b6895aa659b7559ed678e029a5338e535f14
+Version: 3.1.0
+Revision: f52e188fe465c10377f5a2b5765f481cb6fcb2f4
 Security Critical: yes
 
 Steps used to create the current version:
 1. Pull the release from https://github.com/google/protobuf/releases
-2. Add build files (BUILD.gn, proto_library.gni, protobuf.gyp,
-   protobuf_lite.gypi, protobuf_nacl.gyp).
+2. Add build files (BUILD.gn, proto_library.gni).
 
    Be sure to update the list of source files, as additional .cc files and
    headers might have been added -- you need to find the transitive closure of
@@ -25,15 +24,23 @@ Steps used to create the current version:
    $ for patch in patches/*; do patch -s -p1 < $patch; done
 
    For future releases, it will be worth looking into which patches still need
-   to be applied.
-5. Generate descriptor_pb2.py using something like the following steps. Make
-   sure you've regenerated your buildfiles and will build protoc from the
-   newly-modified sources above.
+   to be applied. In case of conflict, update those patches accordingly and save
+   them back in place (i.e. in patches directory).
+5. Generate well_known_types_embed.cc and descriptor_pb2.py using something like
+   the following steps. Make sure you've regenerated your buildfiles and will
+   build js_embed then protoc from the newly-modified sources above.
 
    $ cd $SRC_DIR
+   $ gn gen out/Debug
+   $ ninja -C out/Debug js_embed
+   $ cd third_party/protobuf/src/google/protobuf/compiler/js
+   $ $SRC_DIR/out/Debug/js_embed                                    \
+        ./well_known_types/any.js ./well_known_types/struct.js      \
+        ./well_known_types/timestamp.js > well_known_types_embed.cc
+   $ cd $SRC_DIR
    $ ninja -C out/Debug protoc
    $ cd third_party/protobuf/src
-   $ ../../../out/Debug/protoc --python_out=../python google/protobuf/descriptor.proto
+   $ $SRC_DIR/out/Debug/protoc --python_out=../python google/protobuf/descriptor.proto
 
 6. Add an __init__.py to protobuf/ that adds third_party/six/ to Python path.
 7. Update README.chromium.
@@ -55,13 +62,6 @@ Description of the patches:
   protobuf symbols in Linux .so libraries, so that protobuf can be built as a
   component (see http://crrev.com/179806).
 
-- 0005-fix-include-js-generator.protobuf
-
-  During merge with internal branch, the <> in one of the #includes were
-  accidentally replaced with "", which results in a failure in checkdeps.
-
-  Fixed in https://github.com/google/protobuf/pull/1547.
-
 - 0007-uninline_googleonce.patch
 - 0008-uninline_get_empty_string.patch
 - 0009-uninline-arenastring.patch
@@ -70,9 +70,8 @@ Description of the patches:
   These patches uninline some functions, resulting in a significant reduction
   (somewhere between 500 KB and 1 MB) of binary size.
 
-- 0011-libprotobuf_export.patch
-
-  During merge with internal branch, the dll export attribute was accidentally
-  removed in C++11 mode.
+- 0012-fixes-for-js-embed-cc.patch
 
-  Fixed in https://github.com/google/protobuf/pull/1549
+  Fix include style for well_known_types_embed.cc (genereated in step 5, see
+  above) and also remove it from .gitignore file as we do not generate it in
+  on the fly.