Update //third_party/protobuf to version 3.

third_party/protobuf/cmake/README.md

+This directory contains *CMake* files that can be used to build protobuf
+with *MSVC* on *Windows*. You can build the project from *Command Prompt*
+and using an *Visual Studio* IDE.
+
+You need to have [CMake](http://www.cmake.org), [Visual Studio](https://www.visualstudio.com)
+and optionally [Git](http://git-scm.com) installed on your computer before proceeding.
+
+Most of the instructions will be given to the *Сommand Prompt*, but the same
+actions can be performed using appropriate GUI tools.
+
+Environment Setup
+=================
+
+Open the appropriate *Command Prompt* from the *Start* menu.
+
+For example *VS2013 x64 Native Tools Command Prompt*:
+
+    C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64>
+
+Change to your working directory:
+
+    C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64>cd C:\Path\to
+    C:\Path\to>
+
+Where *C:\Path\to* is path to your real working directory.
+
+Create a folder where protobuf headers/libraries/binaries will be installed after built:
+
+    C:\Path\to>mkdir install
+
+If *cmake* command is not avaliable from *Command Prompt*, add it to system *PATH* variable:
+
+    C:\Path\to>set PATH=%PATH%;C:\Program Files (x86)\CMake\bin
+
+If *git* command is not avaliable from *Command Prompt*, add it to system *PATH* variable:
+
+    C:\Path\to>set PATH=%PATH%;C:\Program Files\Git\cmd
+
+Good. Now you are ready to continue.
+
+Getting Sources
+===============
+
+You can get the latest stable source packages from the
+[releases](https://github.com/google/protobuf/releases) page.
+Or you can type:
+
+     C:\Path\to> git clone -b [release_tag] https://github.com/google/protobuf.git
+
+Where *[release_tag]* is a git tag like *v3.0.0-beta-1* or a branch name like *master*
+if you want to get the latest code.
+
+Go to the project folder:
+
+     C:\Path\to>cd protobuf
+     C:\Path\to\protobuf>
+
+Protobuf unit-tests require gmock to build. If you download protobuf source code
+from the *releases* page, the *gmock* directory should already be there. If you checkout
+the code via `git clone`, this *gmock* directory won't exist and you will have to
+download it manually or skip building protobuf unit-tests.
+
+You can download gmock as follows:
+
+     C:\Path\to\protobuf>git clone -b release-1.7.0 https://github.com/google/googlemock.git gmock
+
+Then go to *gmock* folder and download gtest:
+
+     C:\Path\to\protobuf>cd gmock
+     C:\Path\to\protobuf\gmock>git clone -b release-1.7.0 https://github.com/google/googletest.git gtest
+
+If you absolutely don't want to build and run protobuf unit-tests, skip
+this steps and use protobuf at your own risk.
+
+Now go to *cmake* folder in protobuf sources:
+
+     C:\Path\to\protobuf\gmock>cd ..\cmake
+     C:\Path\to\protobuf\cmake>
+
+Good. Now you are ready to *CMake* configuration.
+
+CMake Configuration
+===================
+
+*CMake* supports a lot of different
+[generators](http://www.cmake.org/cmake/help/latest/manual/cmake-generators.7.html)
+for various native build systems.
+We are only interested in
+[Makefile](http://www.cmake.org/cmake/help/latest/manual/cmake-generators.7.html#makefile-generators)
+and
+[Visual Studio](http://www.cmake.org/cmake/help/latest/manual/cmake-generators.7.html#visual-studio-generators)
+generators.
+
+We will use shadow building to separate the temporary files from the protobuf source code.
+
+Create a temporary *build* folder and change your working directory to it:
+
+     C:\Path\to\protobuf\cmake>mkdir build & cd build
+     C:\Path\to\protobuf\cmake\build>
+
+The *Makefile* generator can build the project in only one configuration, so you need to build
+a separate folder for each configuration.
+
+To start using a *Release* configuration:
+
+     C:\Path\to\protobuf\cmake\build>mkdir release & cd release
+     C:\Path\to\protobuf\cmake\build\release>cmake -G "NMake Makefiles" ^
+     -DCMAKE_BUILD_TYPE=Release ^
+     -DCMAKE_INSTALL_PREFIX=../../../../install ^
+     ../..
+
+It will generate *nmake* *Makefile* in current directory.
+
+To use *Debug* configuration:
+
+     C:\Path\to\protobuf\cmake\build>mkdir debug & cd debug
+     C:\Path\to\protobuf\cmake\build\debug>cmake -G "NMake Makefiles" ^
+     -DCMAKE_BUILD_TYPE=Debug ^
+     -DCMAKE_INSTALL_PREFIX=../../../../install ^
+     ../..
+
+It will generate *nmake* *Makefile* in current directory.
+
+To create *Visual Studio* solution file:
+
+     C:\Path\to\protobuf\cmake\build>mkdir solution & cd solution
+     C:\Path\to\protobuf\cmake\build\solution>cmake -G "Visual Studio 12 2013 Win64" ^
+     -DCMAKE_INSTALL_PREFIX=../../../../install ^
+     ../..
+
+It will generate *Visual Studio* solution file *protobuf.sln* in current directory.
+
+If the *gmock* directory does not exist, and you do not want to build protobuf unit tests,
+you need to add *cmake* command argument `-Dprotobuf_BUILD_TESTS=OFF` to disable testing.
+
+Compiling
+=========
+
+To compile protobuf:
+
+     C:\Path\to\protobuf\cmake\build\release>nmake
+
+or
+
+     C:\Path\to\protobuf\cmake\build\debug>nmake
+
+And wait for the compilation to finish.
+
+If you prefer to use the IDE:
+
+  * Open the generated protobuf.sln file in Microsoft Visual Studio.
+  * Choose "Debug" or "Release" configuration as desired.
+  * From the Build menu, choose "Build Solution".
+
+And wait for the compilation to finish.
+
+Testing
+=======
+
+To run unit-tests:
+
+     C:\Path\to\protobuf\cmake\build\release>nmake check
+
+or
+
+     C:\Path\to\protobuf\cmake\build\debug>nmake check
+
+You can also build project *check* from Visual Studio solution.
+Yes, it may sound strange, but it works.
+
+You should see output similar to:
+
+     Running main() from gmock_main.cc
+     [==========] Running 1546 tests from 165 test cases.
+     
+     ...
+     
+     [==========] 1546 tests from 165 test cases ran. (2529 ms total)
+     [  PASSED  ] 1546 tests.
+
+To run specific tests:
+
+     C:\Path\to\protobuf>cmake\build\release\tests.exe --gtest_filter=AnyTest*
+     Running main() from gmock_main.cc
+     Note: Google Test filter = AnyTest*
+     [==========] Running 3 tests from 1 test case.
+     [----------] Global test environment set-up.
+     [----------] 3 tests from AnyTest
+     [ RUN      ] AnyTest.TestPackAndUnpack
+     [       OK ] AnyTest.TestPackAndUnpack (0 ms)
+     [ RUN      ] AnyTest.TestPackAndUnpackAny
+     [       OK ] AnyTest.TestPackAndUnpackAny (0 ms)
+     [ RUN      ] AnyTest.TestIs
+     [       OK ] AnyTest.TestIs (0 ms)
+     [----------] 3 tests from AnyTest (1 ms total)
+     
+     [----------] Global test environment tear-down
+     [==========] 3 tests from 1 test case ran. (2 ms total)
+     [  PASSED  ] 3 tests.
+
+Note that the tests must be run from the source folder.
+
+If all tests are passed, safely continue.
+
+Installing
+==========
+
+To install protobuf to the specified *install* folder:
+
+     C:\Path\to\protobuf\cmake\build\release>nmake install
+
+or
+
+     C:\Path\to\protobuf\cmake\build\debug>nmake install
+
+You can also build project *INSTALL* from Visual Studio solution.
+It sounds not so strange and it works.
+
+This will create the following folders under the *install* location:
+  * bin - that contains protobuf *protoc.exe* compiler;
+  * inclue - that contains C++ headers and protobuf *.proto files;
+  * lib - that contains linking libraries and *CMake* configuration files for *protobuf* package.
+
+Now you can if needed:
+  * Copy the contents of the include directory to wherever you want to put headers.
+  * Copy protoc.exe wherever you put build tools (probably somewhere in your PATH).
+  * Copy linking libraries libprotobuf[d].lib, libprotobuf-lite[d].lib, and libprotoc[d].lib wherever you put libraries.
+
+To avoid conflicts between the MSVC debug and release runtime libraries, when
+compiling a debug build of your application, you may need to link against a
+debug build of libprotobufd.lib with "d" postfix.  Similarly, release builds should link against
+release libprotobuf.lib library.
+
+DLLs vs. static linking
+=======================
+
+Static linking is now the default for the Protocol Buffer libraries.  Due to
+issues with Win32's use of a separate heap for each DLL, as well as binary
+compatibility issues between different versions of MSVC's STL library, it is
+recommended that you use static linkage only.  However, it is possible to
+build libprotobuf and libprotoc as DLLs if you really want.  To do this,
+do the following:
+
+  * Add an additional flag `-Dprotobuf_BUILD_SHARED_LIBS=ON` when invoking cmake
+  * Follow the same steps as described in the above section.
+  * When compiling your project, make sure to `#define PROTOBUF_USE_DLLS`.
+
+When distributing your software to end users, we strongly recommend that you
+do NOT install libprotobuf.dll or libprotoc.dll to any shared location.
+Instead, keep these libraries next to your binaries, in your application's
+own install directory.  C++ makes it very difficult to maintain binary
+compatibility between releases, so it is likely that future versions of these
+libraries will *not* be usable as drop-in replacements.
+
+If your project is itself a DLL intended for use by third-party software, we
+recommend that you do NOT expose protocol buffer objects in your library's
+public interface, and that you statically link protocol buffers into your
+library.
+
+ZLib support
+============
+
+If you want to include GzipInputStream and GzipOutputStream
+(google/protobuf/io/gzip_stream.h) in libprotobuf, you will need to do a few
+additional steps.
+
+Obtain a copy of the zlib library.  The pre-compiled DLL at zlib.net works.
+You need prepare it:
+
+  * Make sure zlib's two headers are in your `C:\Path\to\install\include` path
+  * Make sure zlib's linking libraries (*.lib file) is in your
+    `C:\Path\to\install\lib` library path.
+
+You can also compile it from source by yourself.
+
+Getting sources:
+
+     C:\Path\to>git clone -b v1.2.8 https://github.com/madler/zlib.git
+     C:\Path\to>cd zlib
+
+Compiling and Installing:
+
+     C:\Path\to\zlib>mkdir build & cd build
+     C:\Path\to\zlib\build>mkdir release & cd release
+     C:\Path\to\zlib\build\release>cmake -G "NMake Makefiles" -DCMAKE_BUILD_TYPE=Release ^
+     -DCMAKE_INSTALL_PREFIX=../../../install ../..
+     C:\Path\to\zlib\build\release>nmake & nmake install
+
+You can make *debug* version or use *Visual Studio* generator also as before for the
+protobuf project.
+
+Now add *bin* folder from *install* to system *PATH*:
+
+     C:\Path\to>set PATH=%PATH%;C:\Path\to\install\bin
+
+You need reconfigure protobuf with flag `-Dprotobuf_WITH_ZLIB=ON` when invoking cmake.
+
+Note that if you have compiled ZLIB yourself, as stated above,
+further disable the option `-Dprotobuf_MSVC_STATIC_RUNTIME=OFF`.
+
+If it reports NOTFOUND for zlib_include or zlib_lib, you might haven't put
+the headers or the .lib file in the right directory.
+
+Build and testing protobuf as usual.
+
+Notes on Compiler Warnings
+==========================
+
+The following warnings have been disabled while building the protobuf libraries
+and compiler.  You may have to disable some of them in your own project as
+well, or live with them.
+
+* C4018 - 'expression' : signed/unsigned mismatch
+* C4146 - unary minus operator applied to unsigned type, result still unsigned
+* C4244 - Conversion from 'type1' to 'type2', possible loss of data.
+* C4251 - 'identifier' : class 'type' needs to have dll-interface to be used by
+  clients of class 'type2'
+* C4267 - Conversion from 'size_t' to 'type', possible loss of data.
+* C4305 - 'identifier' : truncation from 'type1' to 'type2'
+* C4355 - 'this' : used in base member initializer list
+* C4800 - 'type' : forcing value to bool 'true' or 'false' (performance warning)
+* C4996 - 'function': was declared deprecated
+
+C4251 is of particular note, if you are compiling the Protocol Buffer library
+as a DLL (see previous section).  The protocol buffer library uses templates in
+its public interfaces.  MSVC does not provide any reasonable way to export
+template classes from a DLL.  However, in practice, it appears that exporting
+templates is not necessary anyway.  Since the complete definition of any
+template is available in the header files, anyone importing the DLL will just
+end up compiling instances of the templates into their own binary.  The
+Protocol Buffer implementation does not rely on static template members being
+unique, so there should be no problem with this, but MSVC prints warning
+nevertheless.  So, we disable it.  Unfortunately, this warning will also be
+produced when compiling code which merely uses protocol buffers, meaning you
+may have to disable it in your code too.