Add GN build file for OpenSSL.

BUILD.gn

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Config for us and everybody else depending on openssl.
+config("openssl_config") {
+  include_dirs = []
+  if (cpu_arch == "x64") {
+    # Ensure the 64-bit opensslconf.h header is used in preference to the one
+    # in openssl/include.
+    include_dirs += [ "config/x64" ]
+  }
+
+  include_dirs += [ "openssl/include" ]
+}
+
+# Config internal to this build file.
+config("openssl_internal_config") {
+  visibility = ":*"  # Only targets in this file can depend on this.
+}
+
+# The list of OpenSSL files is kept in skia_gn_files.gypi. Read it.

[tfarina, 2014/04/11 18:19:36]

skia_gn_files.gypi? I think you meant openssl.gypi

+gypi_values = exec_script(
+    "//build/gypi_to_gn.py",
+    [ rebase_path("//third_party/openssl/openssl.gypi") ]
+    "scope",
+    [ "//third_party/openssl/openssl.gypi" ])
+
 component("openssl") {
-  external = true
-  gyp_file = "openssl.gyp"
+  sources = gypi_values.openssl_common_sources
+
+  defines = gypi_values.openssl_common_defines
+  defines += [
+    "PURIFY",
+    "MONOLITH",
+  ]
+
+  direct_dependent_configs = [ ":openssl_config" ]
+
+  cflags = []
+
+  # Also gets the include dirs from :openssl_config
+  include_dirs = [
+    ".",
+    "openssl",
+    "openssl/crypto",
+    "openssl/crypto/asn1",
+    "openssl/crypto/evp",
+    "openssl/crypto/modes",
+  ]
+
+  if (is_posix && !is_android) {
+    defines += [
+      # ENGINESDIR must be defined if OPENSSLDIR is.
+      "ENGINESDIR=\"/dev/null\"",
+      # Set to ubuntu default path for convenience. If necessary, override
+      # this at runtime with the SSL_CERT_DIR environment variable.
+      "OPENSSLDIR=\"/etc/ssl\"",
+    ]
+  }
+
+  if (cpu_arch == "x64") {
+    sources += gypi_values.openssl_x86_64_sources
+    sources -= gypi_values.openssl_x86_64_source_excludes
+    defines += gypi_values.openssl_x86_64_defines
+  } else if (cpu_arch == "x86") {
+    sources += gypi_values.openssl_x86_sources
+    sources -= gypi_values.openssl_x86_source_excludes
+    defines += gypi_values.openssl_x86_defines
+  } else if (cpu_arch == "arm") {
+    sources += gypi_values.openssl_arm_sources
+    sources -= gypi_values.openssl_arm_source_excludes
+    defines += gypi_values.openssl_arm_defines
+  } else if (cpu_arch == "mips") {
+    sources += gypi_values.openssl_mips_sources
+    sources -= gypi_values.openssl_mips_source_excludes
+    defines += gypi_values.openssl_mips_defines
+  }
+
+  if (is_clang) {
+    cflags += [

[tfarina, 2014/04/12 02:40:36]

../../third_party/openssl/openssl/crypto/ec/ec_lib.c:71:19: error: unused
variable 'EC_version' [-Werror,-Wunused-const-variable]
static const char EC_version[] = "EC" OPENSSL_VERSION_PTEXT;
                  ^

Do we need -Wno-unused-const-variable here too?

[brettw, 2014/04/12 04:41:49]

Which platform are you compiling on? It worked for me on Linux. 

[tfarina, 2014/04/12 04:48:13]

Try building with clang, it works with gcc though. I'm building on Linux x64 as
well.

$ gn gen out/Release_gn --args="is_debug=false is_clang=true"

+      # OpenSSL has a few |if ((foo == NULL))| checks.
+      "-Wno-parentheses-equality",
+      # OpenSSL uses several function-style macros and then ignores the
+      # returned value.
+      "-Wno-unused-value",
+    ]
+  } else {
+    cflags += [
+      "-Wno-unused-variable",
+    ]
+  }
 }