Import abseil-cpp to third_party

Renamed abseil modules to make them webrtc specific.
Restricted visibility of abseil modules to webrtc packages.

Bug: 171836454
Test: Builds

Change-Id: Icf24c7e3093a77dd9a26e7ec78bd531eb1ad3dec

third_party/abseil-cpp/conanfile.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Note: Conan is supported on a best-effort basis. Abseil doesn't use Conan
+# internally, so we won't know if it stops working. We may ask community
+# members to help us debug any problems that arise.
+
+from conans import ConanFile, CMake, tools
+from conans.errors import ConanInvalidConfiguration
+from conans.model.version import Version
+
+
+class AbseilConan(ConanFile):
+    name = "abseil"
+    url = "https://github.com/abseil/abseil-cpp"
+    homepage = url
+    author = "Abseil <abseil-io@googlegroups.com>"
+    description = "Abseil Common Libraries (C++) from Google"
+    license = "Apache-2.0"
+    topics = ("conan", "abseil", "abseil-cpp", "google", "common-libraries")
+    exports = ["LICENSE"]
+    exports_sources = ["CMakeLists.txt", "CMake/*", "absl/*"]
+    generators = "cmake"
+    settings = "os", "arch", "compiler", "build_type"
+
+    def configure(self):
+        if self.settings.os == "Windows" and \
+           self.settings.compiler == "Visual Studio" and \
+           Version(self.settings.compiler.version.value) < "14":
+            raise ConanInvalidConfiguration("Abseil does not support MSVC < 14")
+
+    def build(self):
+        tools.replace_in_file("CMakeLists.txt", "project(absl CXX)", "project(absl CXX)\ninclude(conanbuildinfo.cmake)\nconan_basic_setup()")
+        cmake = CMake(self)
+        cmake.definitions["BUILD_TESTING"] = False
+        cmake.configure()
+        cmake.build()
+
+    def package(self):
+        self.copy("LICENSE", dst="licenses")
+        self.copy("*.h", dst="include", src=".")
+        self.copy("*.inc", dst="include", src=".")
+        self.copy("*.a", dst="lib", src=".", keep_path=False)
+        self.copy("*.lib", dst="lib", src=".", keep_path=False)
+
+    def package_info(self):
+        if self.settings.os == "Linux":
+            self.cpp_info.libs = ["-Wl,--start-group"]
+        self.cpp_info.libs.extend(tools.collect_libs(self))
+        if self.settings.os == "Linux":
+            self.cpp_info.libs.extend(["-Wl,--end-group", "pthread"])