Remove Windows-related GN build configuration

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index a022d3f19f850c626caded10cb1b9ec2772bca5d..bf73bbd41f5bf9a4d34a18da026f7256ddd9cd98 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -48,15 +48,7 @@ declare_args() {
   # with some utilities such as icecc and ccache. Requires gold and
   # gcc >= 4.8 or clang.
   # http://gcc.gnu.org/wiki/DebugFission
-  use_debug_fission =
-      !is_win && use_gold && linux_use_bundled_binutils && !use_ccache
-
-  if (is_win) {
-    # Whether the VS xtree header has been patched to disable warning 4702. If
-    # it has, then we don't need to disable 4702 (unreachable code warning).
-    # The patch is preapplied to the internal toolchain and hence all bots.
-    msvs_xtree_patched = false
-  }
+  use_debug_fission = use_gold && linux_use_bundled_binutils && !use_ccache
 }
 
 # default_include_dirs ---------------------------------------------------------
@@ -72,9 +64,7 @@ config("default_include_dirs") {
 }
 
 # TODO(GYP): is_ubsan, is_ubsan_vptr
-if (!is_win) {
-  using_sanitizer = is_asan || is_lsan || is_tsan || is_msan
-}
+using_sanitizer = is_asan || is_lsan || is_tsan || is_msan
 
 # compiler ---------------------------------------------------------------------
 #
@@ -91,121 +81,81 @@ config("compiler") {
   ldflags = []
   defines = []
 
-  # In general, Windows is totally different, but all the other builds share
-  # some common GCC configuration. This section sets up Windows and the common
-  # GCC flags, and then we handle the other non-Windows platforms specifically
-  # below.
-  if (is_win) {
-    # Windows compiler flags setup.
-    # -----------------------------
-    cflags += [
-      "/Gy",  # Enable function-level linking.
-      "/GS",  # Enable buffer security checking.
-      "/FS",  # Preserve previous PDB behavior.
-    ]
+  # Common GCC compiler flags setup.
+  # --------------------------------
+  cflags += [ "-fno-strict-aliasing" ]  # See http://crbug.com/32204
+  cflags_cc += [
+    "-fno-threadsafe-statics",
 
-    # Building with Clang on Windows is a work in progress and very
-    # experimental. See crbug.com/82385.
-    # Keep this in sync with the similar block in build/common.gypi
-    if (is_clang) {
-      cflags += [
-        # Many files use intrinsics without including this header.
-        # TODO(hans): Fix those files, or move this to sub-GYPs.
-        "/FIIntrin.h",
-      ]
+    # Not exporting C++ inline functions can generally be applied anywhere
+    # so we do so here. Normal function visibility is controlled by
+    # //build/config/gcc:symbol_visibility_hidden.
+    "-fvisibility-inlines-hidden",
+  ]
 
-      if (visual_studio_version == "2013") {
-        cflags += [ "-fmsc-version=1800" ]
-      } else if (visual_studio_version == "2015") {
-        cflags += [ "-fmsc-version=1900" ]
-      }
+  # Stack protection.
+  if (is_mac) {
+    cflags += [ "-fstack-protector-all" ]
+  } else if (is_linux) {
+    cflags += [
+      "-fstack-protector",
+      "--param=ssp-buffer-size=4",
+    ]
+  }
 
-      if (current_cpu == "x86") {
-        cflags += [
-          "/fallback",
-          "-m32",
-        ]
-      } else {
-        cflags += [ "-m64" ]
-      }
-    }
-  } else {
-    # Common GCC compiler flags setup.
-    # --------------------------------
-    cflags += [ "-fno-strict-aliasing" ]  # See http://crbug.com/32204
-    cflags_cc += [
-      "-fno-threadsafe-statics",
+  # Linker warnings.
+  if (!(is_chromeos && current_cpu == "arm") && !is_mac && !is_ios) {
+    # TODO(jochen): Enable this on chromeos on arm. http://crbug.com/356580
+    ldflags += [ "-Wl,--fatal-warnings" ]
+  }
 
-      # Not exporting C++ inline functions can generally be applied anywhere
-      # so we do so here. Normal function visibility is controlled by
-      # //build/config/gcc:symbol_visibility_hidden.
-      "-fvisibility-inlines-hidden",
+  # Common options for AddressSanitizer, LeakSanitizer, ThreadSanitizer and
+  # MemorySanitizer
+  if (using_sanitizer) {
+    cflags += [
+      "-fno-omit-frame-pointer",
+      "-gline-tables-only",
+    ]
+  }
+  if (is_asan) {
+    asan_blacklist_path =
+        rebase_path("//tools/memory/asan/blacklist.txt", root_build_dir)
+    cflags += [
+      "-fsanitize=address",
+      "-fsanitize-blacklist=$asan_blacklist_path",
     ]
-
-    # Stack protection.
     if (is_mac) {
-      cflags += [ "-fstack-protector-all" ]
-    } else if (is_linux) {
-      cflags += [
-        "-fstack-protector",
-        "--param=ssp-buffer-size=4",
-      ]
-    }
-
-    # Linker warnings.
-    if (!(is_chromeos && current_cpu == "arm") && !is_mac && !is_ios) {
-      # TODO(jochen): Enable this on chromeos on arm. http://crbug.com/356580
-      ldflags += [ "-Wl,--fatal-warnings" ]
-    }
-
-    # Common options for AddressSanitizer, LeakSanitizer, ThreadSanitizer and
-    # MemorySanitizer
-    if (using_sanitizer) {
-      cflags += [
-        "-fno-omit-frame-pointer",
-        "-gline-tables-only",
-      ]
-    }
-    if (is_asan) {
-      asan_blacklist_path =
-          rebase_path("//tools/memory/asan/blacklist.txt", root_build_dir)
-      cflags += [
-        "-fsanitize=address",
-        "-fsanitize-blacklist=$asan_blacklist_path",
-      ]
-      if (is_mac) {
-        cflags += [ "-mllvm -asan-globals=0" ]  # http://crbug.com/352073
-        # TODO(GYP): deal with mac_bundles.
-      }
-    }
-    if (is_lsan) {
-      cflags += [ "-fsanitize=leak" ]
-    }
-    if (is_tsan) {
-      tsan_blacklist_path =
-          rebase_path("//tools/memory/tsan_v2/ignores.txt", root_build_dir)
-      cflags += [
-        "-fsanitize=thread",
-        "-fsanitize-blacklist=$tsan_blacklist_path",
-      ]
-    }
-    if (is_msan) {
-      msan_blacklist_path =
-          rebase_path("//tools/msan/blacklist.txt", root_build_dir)
-      cflags += [
-        "-fsanitize=memory",
-        "-fsanitize-memory-track-origins=$msan_track_origins",
-        "-fsanitize-blacklist=$msan_blacklist_path",
-      ]
+      cflags += [ "-mllvm -asan-globals=0" ]  # http://crbug.com/352073
+      # TODO(GYP): deal with mac_bundles.
     }
+  }
+  if (is_lsan) {
+    cflags += [ "-fsanitize=leak" ]
+  }
+  if (is_tsan) {
+    tsan_blacklist_path =
+        rebase_path("//tools/memory/tsan_v2/ignores.txt", root_build_dir)
+    cflags += [
+      "-fsanitize=thread",
+      "-fsanitize-blacklist=$tsan_blacklist_path",
+    ]
+  }
+  if (is_msan) {
+    msan_blacklist_path =
+        rebase_path("//tools/msan/blacklist.txt", root_build_dir)
+    cflags += [
+      "-fsanitize=memory",
+      "-fsanitize-memory-track-origins=$msan_track_origins",
+      "-fsanitize-blacklist=$msan_blacklist_path",
+    ]
+  }
 
-    if (use_custom_libcxx) {
-      cflags_cc += [ "-nostdinc++" ]
-      include_dirs = [
-        "//buildtools/third_party/libc++/trunk/include",
-        "//buildtools/third_party/libc++abi/trunk/include",
-      ]
-    }
+  if (use_custom_libcxx) {
+    cflags_cc += [ "-nostdinc++" ]
+    include_dirs = [
+      "//buildtools/third_party/libc++/trunk/include",
+      "//buildtools/third_party/libc++abi/trunk/include",
+    ]
   }
 
   if (is_clang && is_debug) {
@@ -505,7 +455,7 @@ config("compiler") {
     # TODO(thakis): Eventually switch this to c++11 instead,
     # http://crbug.com/427584
     cflags_cc += [ "-std=gnu++11" ]
-  } else if (!is_win) {
+  } else {
     cflags_cc += [ "-std=c++11" ]
   }
 
@@ -711,34 +661,6 @@ config("runtime_library") {
   if (is_component_build) {
     # Component mode: dynamic CRT.
     defines += [ "COMPONENT_BUILD" ]
-    if (is_win) {
-      # Since the library is shared, it requires exceptions or will give errors
-      # about things not matching, so keep exceptions on.
-      if (is_debug) {
-        cflags += [ "/MDd" ]
-      } else {
-        cflags += [ "/MD" ]
-      }
-    }
-  } else {
-    # Static CRT.
-    if (is_win) {
-      if (is_debug) {
-        cflags += [ "/MTd" ]
-      } else {
-        cflags += [ "/MT" ]
-      }
-    }
-  }
-
-  if (is_win) {
-    defines += [
-      "__STD_C",
-      "_CRT_RAND_S",
-      "_CRT_SECURE_NO_DEPRECATE",
-      "_HAS_EXCEPTIONS=0",
-      "_SCL_SECURE_NO_DEPRECATE",
-    ]
   }
 
   # Android standard library setup.
@@ -825,196 +747,73 @@ config("runtime_library") {
 
 default_warning_flags = []
 default_warning_flags_cc = []
-if (is_win) {
-  if (!is_clang || current_cpu != "x86") {
-    default_warning_flags += [ "/WX" ]  # Treat warnings as errors.
-  }
 
-  default_warning_flags += [
-    # Warnings permanently disabled:
-
-    # TODO(GYP) The GYP build doesn't have this globally enabled but disabled
-    # for a bunch of individual targets. Re-enable this globally when those
-    # targets are fixed.
-    "/wd4018",  # Comparing signed and unsigned values.
-
-    # C4127: conditional expression is constant
-    # This warning can in theory catch dead code and other problems, but
-    # triggers in far too many desirable cases where the conditional
-    # expression is either set by macros or corresponds some legitimate
-    # compile-time constant expression (due to constant template args,
-    # conditionals comparing the sizes of different types, etc.).  Some of
-    # these can be worked around, but it's not worth it.
-    "/wd4127",
-
-    # C4251: 'identifier' : class 'type' needs to have dll-interface to be
-    #        used by clients of class 'type2'
-    # This is necessary for the shared library build.
-    "/wd4251",
-
-    # C4351: new behavior: elements of array 'array' will be default
-    #        initialized
-    # This is a silly "warning" that basically just alerts you that the
-    # compiler is going to actually follow the language spec like it's
-    # supposed to, instead of not following it like old buggy versions did.
-    # There's absolutely no reason to turn this on.
-    "/wd4351",
-
-    # C4355: 'this': used in base member initializer list
-    # It's commonly useful to pass |this| to objects in a class' initializer
-    # list.  While this warning can catch real bugs, most of the time the
-    # constructors in question don't attempt to call methods on the passed-in
-    # pointer (until later), and annotating every legit usage of this is
-    # simply more hassle than the warning is worth.
-    "/wd4355",
-
-    # C4503: 'identifier': decorated name length exceeded, name was
-    #        truncated
-    # This only means that some long error messages might have truncated
-    # identifiers in the presence of lots of templates.  It has no effect on
-    # program correctness and there's no real reason to waste time trying to
-    # prevent it.
-    "/wd4503",
-
-    # C4611: interaction between 'function' and C++ object destruction is
-    #        non-portable
-    # This warning is unavoidable when using e.g. setjmp/longjmp.  MSDN
-    # suggests using exceptions instead of setjmp/longjmp for C++, but
-    # Chromium code compiles without exception support.  We therefore have to
-    # use setjmp/longjmp for e.g. JPEG decode error handling, which means we
-    # have to turn off this warning (and be careful about how object
-    # destruction happens in such cases).
-    "/wd4611",
-
-    # Warnings to evaluate and possibly fix/reenable later:
-
-    "/wd4100",  # Unreferenced formal function parameter.
-    "/wd4121",  # Alignment of a member was sensitive to packing.
-    "/wd4244",  # Conversion: possible loss of data.
-    "/wd4481",  # Nonstandard extension: override specifier.
-    "/wd4505",  # Unreferenced local function has been removed.
-    "/wd4510",  # Default constructor could not be generated.
-    "/wd4512",  # Assignment operator could not be generated.
-    "/wd4610",  # Class can never be instantiated, constructor required.
-    "/wd4996",  # Deprecated function warning.
-  ]
+# Common GCC warning setup.
+default_warning_flags += [
+  # Enables.
+  "-Wendif-labels",  # Weird old-style text after an #endif.
+  "-Werror",  # Warnings as errors.
 
-  # VS xtree header file needs to be patched or 4702 (unreachable code
-  # warning) is reported if _HAS_EXCEPTIONS=0. Disable the warning if xtree is
-  # not patched.
-  if (!msvs_xtree_patched &&
-      exec_script("../../win_is_xtree_patched.py", [], "value") == 0) {
-    default_warning_flags += [ "/wd4702" ]  # Unreachable code.
-  }
+  # Disables.
+  "-Wno-missing-field-initializers",  # "struct foo f = {0};"
+  "-Wno-unused-parameter",  # Unused function parameters.
+]
 
-  # Building with Clang on Windows is a work in progress and very
-  # experimental. See crbug.com/82385.
-  # Keep this in sync with the similar block in build/common.gypi
-  if (is_clang) {
-    default_warning_flags += [
-      # TODO(hans): Make this list shorter eventually.
-      "-Qunused-arguments",
-      "-Wno-c++11-compat-deprecated-writable-strings",
-      "-Wno-deprecated-declarations",
-      "-Wno-empty-body",
-      "-Wno-enum-conversion",
-      "-Wno-extra-tokens",
-      "-Wno-ignored-attributes",
-      "-Wno-incompatible-pointer-types",
-      "-Wno-int-to-void-pointer-cast",
-      "-Wno-invalid-noreturn",
-      "-Wno-logical-op-parentheses",
-      "-Wno-microsoft",
-      "-Wno-missing-braces",
-      "-Wno-missing-declarations",
-      "-Wno-msvc-include",
-      "-Wno-null-dereference",
-      "-Wno-overloaded-virtual",
-      "-Wno-parentheses",
-      "-Wno-pointer-sign",
-      "-Wno-reorder",
-      "-Wno-return-type-c-linkage",
-      "-Wno-self-assign",
-      "-Wno-sometimes-uninitialized",
-      "-Wno-switch",
-      "-Wno-tautological-compare",
-      "-Wno-unknown-pragmas",
-      "-Wno-unsequenced",
-      "-Wno-unused-function",
-      "-Wno-unused-private-field",
-      "-Wno-unused-value",
-      "-Wno-unused-variable",
-      "-Wno-unused-local-typedef",  # http://crbug.com/411648
-      "-Wno-inconsistent-missing-override",  #http://crbug.com/428099
-    ]
-  }
-} else {
-  # Common GCC warning setup.
-  default_warning_flags += [
-    # Enables.
-    "-Wendif-labels",  # Weird old-style text after an #endif.
-    "-Werror",  # Warnings as errors.
-
-    # Disables.
-    "-Wno-missing-field-initializers",  # "struct foo f = {0};"
-    "-Wno-unused-parameter",  # Unused function parameters.
-  ]
-
-  if (is_mac) {
-    default_warning_flags += [ "-Wnewline-eof" ]
-    if (!is_nacl) {
-      # When compiling Objective-C, warns if a method is used whose
-      # availability is newer than the deployment target. This is not
-      # required when compiling Chrome for iOS.
-      default_warning_flags += [ "-Wpartial-availability" ]
-    }
+if (is_mac) {
+  default_warning_flags += [ "-Wnewline-eof" ]
+  if (!is_nacl) {
+    # When compiling Objective-C, warns if a method is used whose
+    # availability is newer than the deployment target. This is not
+    # required when compiling Chrome for iOS.
+    default_warning_flags += [ "-Wpartial-availability" ]
   }
+}
 
-  if (gcc_version >= 48) {
-    default_warning_flags_cc += [
-      # See comment for -Wno-c++11-narrowing.
-      "-Wno-narrowing",
+if (gcc_version >= 48) {
+  default_warning_flags_cc += [
+    # See comment for -Wno-c++11-narrowing.
+    "-Wno-narrowing",
 
-      # TODO(thakis): Remove, http://crbug.com/263960
-      "-Wno-literal-suffix",
-    ]
-  }
+    # TODO(thakis): Remove, http://crbug.com/263960
+    "-Wno-literal-suffix",
+  ]
+}
 
-  # Suppress warnings about ABI changes on ARM (Clang doesn't give this
-  # warning).
-  if (current_cpu == "arm" && !is_clang) {
-    default_warning_flags += [ "-Wno-psabi" ]
-  }
+# Suppress warnings about ABI changes on ARM (Clang doesn't give this
+# warning).
+if (current_cpu == "arm" && !is_clang) {
+  default_warning_flags += [ "-Wno-psabi" ]
+}
 
-  if (is_android) {
-    # Disable any additional warnings enabled by the Android build system but
-    # which chromium does not build cleanly with (when treating warning as
-    # errors).
-    default_warning_flags += [
-      "-Wno-extra",
-      "-Wno-ignored-qualifiers",
-      "-Wno-type-limits",
-    ]
-    default_warning_flags_cc += [
-      # Disabling c++0x-compat should be handled in WebKit, but
-      # this currently doesn't work because gcc_version is not set
-      # correctly when building with the Android build system.
-      # TODO(torne): Fix this in WebKit.
-      "-Wno-error=c++0x-compat",
-
-      # Other things unrelated to -Wextra:
-      "-Wno-non-virtual-dtor",
-      "-Wno-sign-promo",
-    ]
-  }
+if (is_android) {
+  # Disable any additional warnings enabled by the Android build system but
+  # which chromium does not build cleanly with (when treating warning as
+  # errors).
+  default_warning_flags += [
+    "-Wno-extra",
+    "-Wno-ignored-qualifiers",
+    "-Wno-type-limits",
+  ]
+  default_warning_flags_cc += [
+    # Disabling c++0x-compat should be handled in WebKit, but
+    # this currently doesn't work because gcc_version is not set
+    # correctly when building with the Android build system.
+    # TODO(torne): Fix this in WebKit.
+    "-Wno-error=c++0x-compat",
+
+    # Other things unrelated to -Wextra:
+    "-Wno-non-virtual-dtor",
+    "-Wno-sign-promo",
+  ]
+}
 
-  if (gcc_version >= 48) {
-    # Don't warn about the "typedef 'foo' locally defined but not used"
-    # for gcc 4.8.
-    # TODO: remove this flag once all builds work. See crbug.com/227506
-    default_warning_flags += [ "-Wno-unused-local-typedefs" ]
-  }
+if (gcc_version >= 48) {
+  # Don't warn about the "typedef 'foo' locally defined but not used"
+  # for gcc 4.8.
+  # TODO: remove this flag once all builds work. See crbug.com/227506
+  default_warning_flags += [ "-Wno-unused-local-typedefs" ]
 }
+
 if (is_clang) {
   default_warning_flags += [
     # This warns on using ints as initializers for floats in
@@ -1070,39 +869,36 @@ if (is_clang) {
 # part of Chromium.
 
 config("chromium_code") {
-  if (is_win) {
-    cflags = [ "/W4" ]  # Warning level 4.
-  } else {
-    cflags = [
-      "-Wall",
-
-      # GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
-      # so we specify it explicitly.
-      # TODO(fischman): remove this if http://llvm.org/PR10448 obsoletes it.
-      # http://code.google.com/p/chromium/issues/detail?id=90453
-      "-Wsign-compare",
-    ]
+  cflags = [
+    "-Wall",
+
+    # GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
+    # so we specify it explicitly.
+    # TODO(fischman): remove this if http://llvm.org/PR10448 obsoletes it.
+    # http://code.google.com/p/chromium/issues/detail?id=90453
+    "-Wsign-compare",
+  ]
 
-    # In Chromium code, we define __STDC_foo_MACROS in order to get the
-    # C99 macros on Mac and Linux.
-    defines = [
-      "__STDC_CONSTANT_MACROS",
-      "__STDC_FORMAT_MACROS",
-    ]
+  # In Chromium code, we define __STDC_foo_MACROS in order to get the
+  # C99 macros on Mac and Linux.
+  defines = [
+    "__STDC_CONSTANT_MACROS",
+    "__STDC_FORMAT_MACROS",
+  ]
 
-    if (!is_debug && !using_sanitizer &&
-        (!is_linux || !is_clang || is_official_build)) {
-      # _FORTIFY_SOURCE isn't really supported by Clang now, see
-      # http://llvm.org/bugs/show_bug.cgi?id=16821.
-      # It seems to work fine with Ubuntu 12 headers though, so use it in
-      # official builds.
-      #
-      # Non-chromium code is not guaranteed to compile cleanly with
-      # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
-      # disabled, so only do that for Release build.
-      defines += [ "_FORTIFY_SOURCE=2" ]
-    }
+  if (!is_debug && !using_sanitizer &&
+      (!is_linux || !is_clang || is_official_build)) {
+    # _FORTIFY_SOURCE isn't really supported by Clang now, see
+    # http://llvm.org/bugs/show_bug.cgi?id=16821.
+    # It seems to work fine with Ubuntu 12 headers though, so use it in
+    # official builds.
+    #
+    # Non-chromium code is not guaranteed to compile cleanly with
+    # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
+    # disabled, so only do that for Release build.
+    defines += [ "_FORTIFY_SOURCE=2" ]
   }
+
   cflags += default_warning_flags
   cflags_cc = default_warning_flags_cc
 }
@@ -1111,19 +907,6 @@ config("no_chromium_code") {
   cflags_cc = []
   defines = []
 
-  if (is_win) {
-    cflags += [
-      "/W3",  # Warning level 3.
-      "/wd4800",  # Disable warning when forcing value to bool.
-      "/wd4267",  # TODO(jschuh): size_t to int.
-      "/wd4996",  # Deprecated function warning.
-    ]
-    defines += [
-      "_CRT_NONSTDC_NO_WARNINGS",
-      "_CRT_NONSTDC_NO_DEPRECATE",
-    ]
-  }
-
   if (is_linux) {
     # Don't warn about ignoring the return value from e.g. close(). This is
     # off by default in some gccs but on by default in others. BSD systems do
@@ -1155,16 +938,9 @@ config("no_chromium_code") {
 # Allows turning Run-Time Type Identification on or off.
 
 config("rtti") {
-  if (is_win) {
-    cflags_cc = [ "/GR" ]
-  }
 }
 config("no_rtti") {
-  if (is_win) {
-    cflags_cc = [ "/GR-" ]
-  } else {
-    cflags_cc = [ "-fno-rtti" ]
-  }
+  cflags_cc = [ "-fno-rtti" ]
 }
 
 # Warnings ---------------------------------------------------------------------
@@ -1173,8 +949,7 @@ config("no_rtti") {
 # destructors, which will slow down closing the program.
 # TODO(thakis): Make this a blacklist instead, http://crbug.com/101600
 config("wexit_time_destructors") {
-  # TODO: Enable on Windows too, http://crbug.com/404525
-  if (is_clang && !is_win) {
+  if (is_clang) {
     cflags = [ "-Wexit-time-destructors" ]
   }
 }
@@ -1190,9 +965,6 @@ config("wexit_time_destructors") {
 #
 # TODO(jschuh): crbug.com/167187 fix this and delete this config.
 config("no_size_t_to_int_warning") {
-  if (is_win && current_cpu == "x64") {
-    cflags = [ "/wd4267" ]
-  }
 }
 
 # Some code presumes that pointers to structures/objects are compatible
@@ -1216,72 +988,52 @@ config("no_incompatible_pointer_warnings") {
 #   configs += [ "//build/config/compiler/optimize_max" ]
 
 # Shared settings for both "optimize" and "optimize_max" configs.
-if (is_win) {
-  common_optimize_on_cflags = [
-    "/O2",
-    "/Ob2",  # both explicit and auto inlining.
-    "/Oy-",  # disable omitting frame pointers, must be after /o2.
-    "/Os",  # favor size over speed.
-  ]
-  if (!is_asan) {
-    common_optimize_on_cflags += [
-      # Put data in separate COMDATs. This allows the linker
-      # to put bit-identical constants at the same address even if
-      # they're unrelated constants, which saves binary size.
-      # This optimization can't be used when ASan is enabled because
-      # it is not compatible with the ASan ODR checker.
-      "/Gw",
-    ]
-  }
-  common_optimize_on_ldflags = [ "/OPT:REF" ]
-} else {
-  common_optimize_on_cflags = [
-    # Don't emit the GCC version ident directives, they just end up in the
-    # .comment section taking up binary size.
-    "-fno-ident",
-
-    # Put data and code in their own sections, so that unused symbols
-    # can be removed at link time with --gc-sections.
-    "-fdata-sections",
-    "-ffunction-sections",
-  ]
-  common_optimize_on_ldflags = []
-
-  if (is_android) {
-    if (!using_sanitizer) {
-      common_optimize_on_cflags += [ "-fomit-frame-pointer" ]
-    }
-
-    # TODO(jdduke) Re-enable on mips after resolving linking
-    # issues with libc++ (crbug.com/456380).
-    if (current_cpu != "mipsel" && current_cpu != "mips64el") {
-      common_optimize_on_ldflags += [
-        # Warn in case of text relocations.
-        "-Wl,--warn-shared-textrel",
-      ]
-    }
+common_optimize_on_cflags = [
+  # Don't emit the GCC version ident directives, they just end up in the
+  # .comment section taking up binary size.
+  "-fno-ident",
+
+  # Put data and code in their own sections, so that unused symbols
+  # can be removed at link time with --gc-sections.
+  "-fdata-sections",
+  "-ffunction-sections",
+]
+common_optimize_on_ldflags = []
+
+if (is_android) {
+  if (!using_sanitizer) {
+    common_optimize_on_cflags += [ "-fomit-frame-pointer" ]
   }
 
-  if (is_mac) {
-    if (symbol_level == 2) {
-      # Mac dead code stripping requires symbols.
-      common_optimize_on_ldflags += [ "-Wl,-dead_strip" ]
-    }
-  } else {
-    # Non-Mac Posix linker flags.
+  # TODO(jdduke) Re-enable on mips after resolving linking
+  # issues with libc++ (crbug.com/456380).
+  if (current_cpu != "mipsel" && current_cpu != "mips64el") {
     common_optimize_on_ldflags += [
-      # Specifically tell the linker to perform optimizations.
-      # See http://lwn.net/Articles/192624/ .
-      "-Wl,-O1",
-      "-Wl,--gc-sections",
+      # Warn in case of text relocations.
+      "-Wl,--warn-shared-textrel",
     ]
+  }
+}
 
-    if (!using_sanitizer) {
-      # Functions interposed by the sanitizers can make ld think
-      # that some libraries aren't needed when they actually are,
-      # http://crbug.com/234010. As workaround, disable --as-needed.
-      common_optimize_on_ldflags += [ "-Wl,--as-needed" ]
-    }
+if (is_mac) {
+  if (symbol_level == 2) {
+    # Mac dead code stripping requires symbols.
+    common_optimize_on_ldflags += [ "-Wl,-dead_strip" ]
+  }
+} else {
+  # Non-Mac Posix linker flags.
+  common_optimize_on_ldflags += [
+    # Specifically tell the linker to perform optimizations.
+    # See http://lwn.net/Articles/192624/ .
+    "-Wl,-O1",
+    "-Wl,--gc-sections",
+  ]
+
+  if (!using_sanitizer) {
+    # Functions interposed by the sanitizers can make ld think
+    # that some libraries aren't needed when they actually are,
+    # http://crbug.com/234010. As workaround, disable --as-needed.
+    common_optimize_on_ldflags += [ "-Wl,--as-needed" ]
   }
 }
 
@@ -1289,9 +1041,7 @@ if (is_win) {
 config("optimize") {
   cflags = common_optimize_on_cflags
   ldflags = common_optimize_on_ldflags
-  if (is_win) {
-    cflags += [ "/Os" ]  # favor size over speed.
-  } else if (is_android || is_ios) {
+  if (is_android || is_ios) {
     cflags += [ "-Os" ]  # Favor size over speed.
   } else {
     cflags += [ "-O2" ]
@@ -1300,13 +1050,7 @@ config("optimize") {
 
 # Turn off optimizations.
 config("no_optimize") {
-  if (is_win) {
-    cflags = [
-      "/Od",  # Disable optimization.
-      "/Ob0",  # Disable all inlining (on by default).
-      "/RTC1",  # Runtime checks for stack frame and uninitialized variables.
-    ]
-  } else if (is_android && !android_full_debug) {
+  if (is_android && !android_full_debug) {
     # On Android we kind of optimize some things that don't affect debugging
     # much even when optimization is disabled to get the binary size down.
     cflags = [
@@ -1329,27 +1073,8 @@ config("no_optimize") {
 config("optimize_max") {
   cflags = common_optimize_on_cflags
   ldflags = common_optimize_on_ldflags
-  if (is_win) {
-    cflags -= [ "/Os" ]
-    cflags += [ "/Ot" ]  # Favor speed over size.
-    if (is_official_build) {
-      # TODO(GYP): TODO(dpranke): Should these only be on in an official
-      # build, or on all the time? For now we'll require official build so
-      # that the compile is clean.
-      cflags += [
-        "/GL",  # Whole program optimization.
 
-        # Disable Warning 4702 ("Unreachable code") for the WPO/PGO builds.
-        # Probably anything that this would catch that wouldn't be caught in a
-        # normal build isn't going to actually be a bug, so the incremental
-        # value of C4702 for PGO builds is likely very small.
-        "/wd4702",
-      ]
-      ldflags += [ "/LTCG" ]
-    }
-  } else {
-    cflags += [ "-O2" ]
-  }
+  cflags += [ "-O2" ]
 }
 
 # The default optimization applied to all targets. This will be equivalent to
@@ -1369,43 +1094,26 @@ config("default_optimization") {
 # Symbols ----------------------------------------------------------------------
 
 config("symbols") {
-  if (is_win) {
-    import("//build/toolchain/goma.gni")
-    if (use_goma) {
-      cflags = [ "/Z7" ]  # No PDB file
-    } else {
-      cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
-    }
-    ldflags = [ "/DEBUG" ]
-  } else {
-    cflags = [ "-g2" ]
-    if (use_debug_fission) {
-      cflags += [ "-gsplit-dwarf" ]
-    }
-    asmflags = cflags
-    ldflags = []
+  cflags = [ "-g2" ]
+  if (use_debug_fission) {
+    cflags += [ "-gsplit-dwarf" ]
   }
+  asmflags = cflags
+  ldflags = []
 }
 
 config("minimal_symbols") {
-  if (is_win) {
-    # Linker symbols for backtraces only.
-    ldflags = [ "/DEBUG" ]
-  } else {
-    cflags = [ "-g1" ]
-    if (use_debug_fission) {
-      cflags += [ "-gsplit-dwarf" ]
-    }
-    asmflags = cflags
-    ldflags = []
+  cflags = [ "-g1" ]
+  if (use_debug_fission) {
+    cflags += [ "-gsplit-dwarf" ]
   }
+  asmflags = cflags
+  ldflags = []
 }
 
 config("no_symbols") {
-  if (!is_win) {
-    cflags = [ "-g0" ]
-    asmflags = cflags
-  }
+  cflags = [ "-g0" ]
+  asmflags = cflags
 }
 
 # Default symbols.