Revert of Remove typedefs.h from webrtc/ root (part 1)

webrtc/typedefs.h

Index: webrtc/typedefs.h
diff --git a/webrtc/typedefs.h b/webrtc/typedefs.h
index 84a7c08ee5449a2574eb5c01b772145f3e3db95b..bd0bee75c2a8c13234fb402aa3a99abd0fcf639e 100644
--- a/webrtc/typedefs.h
+++ b/webrtc/typedefs.h
@@ -8,14 +8,118 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+// This file contains platform-specific typedefs and defines.
+// Much of it is derived from Chromium's build/build_config.h.
+
 #ifndef WEBRTC_TYPEDEFS_H_
 #define WEBRTC_TYPEDEFS_H_
 
-// TODO(solenberg): Delete this file once downstream projects have been updated.
+// Processor architecture detection.  For more info on what's defined, see:
+//   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
+//   http://www.agner.org/optimize/calling_conventions.pdf
+//   or with gcc, run: "echo | gcc -E -dM -"
+#if defined(_M_X64) || defined(__x86_64__)
+#define WEBRTC_ARCH_X86_FAMILY
+#define WEBRTC_ARCH_X86_64
+#define WEBRTC_ARCH_64_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(__aarch64__)
+#define WEBRTC_ARCH_ARM_FAMILY
+#define WEBRTC_ARCH_64_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(_M_IX86) || defined(__i386__)
+#define WEBRTC_ARCH_X86_FAMILY
+#define WEBRTC_ARCH_X86
+#define WEBRTC_ARCH_32_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(__ARMEL__)
+#define WEBRTC_ARCH_ARM_FAMILY
+#define WEBRTC_ARCH_32_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(__MIPSEL__)
+#define WEBRTC_ARCH_MIPS_FAMILY
+#if defined(__LP64__)
+#define WEBRTC_ARCH_64_BITS
+#else
+#define WEBRTC_ARCH_32_BITS
+#endif
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#elif defined(__pnacl__)
+#define WEBRTC_ARCH_32_BITS
+#define WEBRTC_ARCH_LITTLE_ENDIAN
+#else
+#error Please add support for your architecture in typedefs.h
+#endif
+
+#if !(defined(WEBRTC_ARCH_LITTLE_ENDIAN) ^ defined(WEBRTC_ARCH_BIG_ENDIAN))
+#error Define either WEBRTC_ARCH_LITTLE_ENDIAN or WEBRTC_ARCH_BIG_ENDIAN
+#endif
+
+// TODO(zhongwei.yao): WEBRTC_CPU_DETECTION is only used in one place; we should
+// probably just remove it.
+#if (defined(WEBRTC_ARCH_X86_FAMILY) && !defined(__SSE2__))
+#define WEBRTC_CPU_DETECTION
+#endif
 
 #include <stdint.h>
 
-#include "webrtc/rtc_base/arch.h"
-#include "webrtc/rtc_base/annotations.h"
+// Annotate a function indicating the caller must examine the return value.
+// Use like:
+//   int foo() RTC_WARN_UNUSED_RESULT;
+// To explicitly ignore a result, cast to void.
+// TODO(kwiberg): Remove when we can use [[nodiscard]] from C++17.
+#if defined(__clang__)
+#define RTC_WARN_UNUSED_RESULT __attribute__((__warn_unused_result__))
+#elif defined(__GNUC__)
+// gcc has a __warn_unused_result__ attribute, but you can't quiet it by
+// casting to void, so we don't use it.
+#define RTC_WARN_UNUSED_RESULT
+#else
+#define RTC_WARN_UNUSED_RESULT
+#endif
+
+// Put after a variable that might not be used, to prevent compiler warnings:
+//   int result ATTRIBUTE_UNUSED = DoSomething();
+//   assert(result == 17);
+// Deprecated since it only works with GCC & clang. See RTC_UNUSED below.
+// TODO(terelius): Remove.
+#ifndef ATTRIBUTE_UNUSED
+#if defined(__GNUC__) || defined(__clang__)
+#define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#else
+#define ATTRIBUTE_UNUSED
+#endif
+#endif
+
+// Macro to be used for switch-case fallthrough (required for enabling
+// -Wimplicit-fallthrough warning on Clang).
+#ifndef FALLTHROUGH
+#if defined(__clang__)
+#define FALLTHROUGH() [[clang::fallthrough]]
+#else
+#define FALLTHROUGH() do { } while (0)
+#endif
+#endif
+
+#ifndef NO_RETURN
+// Annotate a function that will not return control flow to the caller.
+#if defined(_MSC_VER)
+#define NO_RETURN __declspec(noreturn)
+#elif defined(__GNUC__)
+#define NO_RETURN __attribute__ ((__noreturn__))
+#else
+#define NO_RETURN
+#endif
+#endif
+
+// Prevent the compiler from warning about an unused variable. For example:
+//   int result = DoSomething();
+//   assert(result == 17);
+//   RTC_UNUSED(result);
+// Note: In most cases it is better to remove the unused variable rather than
+// suppressing the compiler warning.
+#ifndef RTC_UNUSED
+#define RTC_UNUSED(x) static_cast<void>(x)
+#endif  // RTC_UNUSED
 
 #endif  // WEBRTC_TYPEDEFS_H_