diff --git a/config/BUILDCONFIG.gn b/config/BUILDCONFIG.gn
index 4630b2f3b..71161b086 100644
--- a/config/BUILDCONFIG.gn
+++ b/config/BUILDCONFIG.gn
@@ -111,14 +111,6 @@ if (current_os == "") {
 #   even if the value is overridden, which is wasteful. See first bullet.
 
 declare_args() {
-  # How many symbols to include in the build. This affects the performance of
-  # the build since the symbols are large and dealing with them is slow.
-  #   2 means regular build with symbols.
-  #   1 means minimal symbols, usually enough for backtraces only.
-  #   0 means no symbols.
-  #   -1 means auto-set (off in release, regular in debug).
-  symbol_level = -1
-
   # Component build.
   is_component_build = false
 
@@ -133,18 +125,6 @@ declare_args() {
   is_clang = current_os == "mac" || current_os == "ios" ||
              current_os == "linux" || current_os == "chromeos"
 
-  # Compile for Address Sanitizer to find memory bugs.
-  is_asan = false
-
-  # Compile for Leak Sanitizer to find leaks.
-  is_lsan = false
-
-  # Compile for Memory Sanitizer to find uninitialized reads.
-  is_msan = false
-
-  # Compile for Thread Sanitizer to find threading bugs.
-  is_tsan = false
-
   if (current_os == "chromeos") {
     # Allows the target toolchain to be injected as arguments. This is needed
     # to support the CrOS build system which supports per-build-configuration
@@ -176,7 +156,7 @@ declare_args() {
 # and there's only one config to remove that's the same in all cases for
 # targets that want to override it. It also means that the associated flags can
 # be non-global.
-using_new_global_compiler_configs = false
+using_new_global_compiler_configs = true
 
 # To assist in a multi-sided landing of updating the default optimization
 # config. When false, this file sets up the default optimization config to be
@@ -184,7 +164,15 @@ using_new_global_compiler_configs = false
 # always set the config "default_optimization".
 #
 # TODO(brettw) remove this when all repos are updated.
-using_new_optimization_config = false
+using_new_optimization_config = true
+
+# To assist in a multi-sided landing of updating the default optimization
+# config. When false, this file sets up the default optimization config to be
+# either "no_optimize" (debug) or "optimize" (release). When true it will
+# always set the config "default_optimization".
+#
+# TODO(brettw) remove this when all repos are updated.
+using_new_optimization_config = true
 
 # =============================================================================
 # OS DEFINITIONS
@@ -386,16 +374,6 @@ if (!is_chromeos) {
 # your platform/toolkit/feature doesn't apply.
 set_sources_assignment_filter(sources_assignment_filter)
 
-# =============================================================================
-# BUILD OPTIONS
-# =============================================================================
-
-# These Sanitizers all imply using the Clang compiler. On Windows they either
-# don't work or work differently.
-if (!is_clang && (is_asan || is_lsan || is_tsan || is_msan)) {
-  is_clang = true
-}
-
 # =============================================================================
 # TARGET DEFAULTS
 # =============================================================================
@@ -413,6 +391,8 @@ _native_compiler_configs = [
   "//build/config/compiler:compiler_arm_fpu",
   "//build/config/compiler:chromium_code",
   "//build/config/compiler:default_include_dirs",
+  "//build/config/compiler:default_optimization",
+  "//build/config/compiler:default_symbols",
   "//build/config/compiler:no_rtti",
   "//build/config/compiler:runtime_library",
 ]
@@ -441,7 +421,6 @@ if (is_linux) {
 } else if (is_mac) {
   _native_compiler_configs += [ "//build/config/mac:sdk" ]
 } else if (is_ios) {
-  _native_compiler_configs += [ "//build/config/ios:sdk" ]
 } else if (is_android) {
   _native_compiler_configs += [ "//build/config/android:sdk" ]
 }
@@ -453,41 +432,12 @@ if (is_clang && !is_nacl) {
   ]
 }
 
-# Optimizations and debug checking.
+# Debug/release-related defines.
 if (is_debug) {
   _native_compiler_configs += [ "//build/config:debug" ]
-  _default_optimization_config = "//build/config/compiler:no_optimize"
 } else {
   _native_compiler_configs += [ "//build/config:release" ]
-  _default_optimization_config = "//build/config/compiler:optimize"
 }
-_native_compiler_configs += [ _default_optimization_config ]
-
-# If it wasn't manually set, set to an appropriate default.
-if (symbol_level == -1) {
-  # Linux is slowed by having symbols as part of the target binary, whereas
-  # Mac and Windows have them separate, so in Release Linux, default them off.
-  if (is_debug || !is_linux) {
-    symbol_level = 2
-  } else if (is_asan || is_lsan || is_tsan || is_msan) {
-    # Sanitizers require symbols for filename suppressions to work.
-    symbol_level = 1
-  } else {
-    symbol_level = 0
-  }
-}
-
-# Symbol setup.
-if (symbol_level == 2) {
-  _default_symbols_config = "//build/config/compiler:symbols"
-} else if (symbol_level == 1) {
-  _default_symbols_config = "//build/config/compiler:minimal_symbols"
-} else if (symbol_level == 0) {
-  _default_symbols_config = "//build/config/compiler:no_symbols"
-} else {
-  assert(false, "Bad value for symbol_level.")
-}
-_native_compiler_configs += [ _default_symbols_config ]
 
 # Windows linker setup for EXEs and DLLs.
 if (is_win) {
diff --git a/config/compiler/BUILD.gn b/config/compiler/BUILD.gn
index 329173197..637d05555 100644
--- a/config/compiler/BUILD.gn
+++ b/config/compiler/BUILD.gn
@@ -4,6 +4,9 @@
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
+import("//build/config/compiler/compiler.gni")
+import("//build/toolchain/ccache.gni")
+
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
@@ -17,9 +20,6 @@ if (is_win) {
   import("//build/config/win/visual_studio_version.gni")
 }
 
-import("//build/toolchain/ccache.gni")
-import("//build/config/sanitizers/sanitizers.gni")
-
 declare_args() {
   # Normally, Android builds are lightly optimized, even for debug builds, to
   # keep binary size down. Setting this flag to true disables such optimization
@@ -84,11 +84,6 @@ config("default_include_dirs") {
   ]
 }
 
-# TODO(GYP) bug 527515: is_ubsan, is_ubsan_vptr
-if (!is_win) {
-  using_sanitizer = is_asan || is_lsan || is_tsan || is_msan
-}
-
 # compiler ---------------------------------------------------------------------
 #
 # Base compiler configuration.
@@ -1211,14 +1206,15 @@ config("no_incompatible_pointer_warnings") {
 
 # Optimization -----------------------------------------------------------------
 #
-# Note that BUILDCONFIG.gn sets up a variable "default_optimization_config"
-# which it will assign to the config it implicitly applies to every target. If
-# you want to override the optimization level for your target, remove this
-# config (which will expand differently for debug or release builds), and then
-# add back the one you want to override it with:
+# The BUILDCONFIG file sets the "default_optimization" config on targets by
+# default. It will be equivalent to either "optimize" (release) or
+# "no_optimize" (debug) optimization configs.
 #
-#   configs -= default_optimization_config
-#   configs += [ "//build/config/compiler/optimize_max" ]
+# You can override the optimization level on a per-target basis by removing the
+# default config and then adding the named one you want:
+#
+#   configs -= [ "//build/config/compiler:default_optimization" ]
+#   configs += [ "//build/config/compiler:optimize_max" ]
 
 # Shared settings for both "optimize" and "optimize_max" configs.
 # IMPORTANT: On Windows "/O1" and "/O2" must go before the common flags.
@@ -1301,43 +1297,57 @@ if (is_win) {
   }
 }
 
-# Default "optimization on" config. On Windows, this favors size over speed.
+# Default "optimization on" config. Set up variables so the
+# "default_optimization" config can re-use these settings.
+if (is_win) {
+  # Favor size over speed, /O1 must be before the common flags. The GYP
+  # build also specifies /Os and /GF but these are implied by /O1.
+  optimize_cflags = [ "/O1" ] + common_optimize_on_cflags + [ "/Oi" ]
+} else if (is_android || is_ios) {
+  # Favor size over speed.
+  optimize_cflags = [ "-Os" ] + common_optimize_on_cflags
+} else {
+  # Linux & Mac favor speed over size.
+  # TODO(brettw) it's weird that Mac and desktop Linux are different. We should
+  # explore favoring size over speed in this case as well.
+  optimize_cflags = [ "-O2" ] + common_optimize_on_cflags
+}
+optimize_ldflags = common_optimize_on_ldflags
+
 config("optimize") {
-  if (is_win) {
-    # Favor size over speed, /O1 must be before the common flags. The GYP
-    # build also specifies /Os and /GF but these are implied by /O1.
-    cflags = [ "/O1" ] + common_optimize_on_cflags + [ "/Oi" ]
-  } else if (is_android || is_ios) {
-    cflags = [ "-Os" ] + common_optimize_on_cflags  # Favor size over speed.
-  } else {
-    cflags = [ "-O2" ] + common_optimize_on_cflags
-  }
-  ldflags = common_optimize_on_ldflags
+  cflags = optimize_cflags
+  ldflags = optimize_ldflags
 }
 
-# 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) {
-    # 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 = [
-      "-Os",
-      "-fdata-sections",
-      "-ffunction-sections",
-    ]
-    if (!using_sanitizer) {
-      cflags += [ "-fomit-frame-pointer" ]
-    }
-    ldflags = common_optimize_on_ldflags
-  } else {
-    cflags = [ "-O0" ]
+# Turn off optimizations. Set up variables so the
+# "default_optimization" config can re-use these settings.
+if (is_win) {
+  no_optimize_cflags = [
+    "/Od",  # Disable optimization.
+    "/Ob0",  # Disable all inlining (on by default).
+    "/RTC1",  # Runtime checks for stack frame and uninitialized variables.
+  ]
+  no_optimize_ldflags = []
+} else 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.
+  no_optimize_cflags = [
+    "-Os",
+    "-fdata-sections",
+    "-ffunction-sections",
+  ]
+  if (!using_sanitizer) {
+    no_optimize_cflags += [ "-fomit-frame-pointer" ]
   }
+  no_optimize_ldflags = common_optimize_on_ldflags
+} else {
+  no_optimize_cflags = [ "-O0" ]
+  no_optimize_ldflags = []
+}
+
+config("no_optimize") {
+  cflags = no_optimize_cflags
+  ldflags = no_optimize_ldflags
 }
 
 # Turns up the optimization level. On Windows, this implies whole program
@@ -1368,53 +1378,105 @@ config("optimize_max") {
   }
 }
 
+# The default optimization applied to all targets. This will be equivalent to
+# either "optimize" or "no_optimize", depending on the build flags.
+config("default_optimization") {
+  if (is_debug) {
+    cflags = no_optimize_cflags
+    ldflags = no_optimize_ldflags
+  } else {
+    cflags = optimize_cflags
+    ldflags = optimize_ldflags
+  }
+}
+
 # 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.
-    }
-    if (is_win_fastlink) {
-      # Tell VS 2015+ to create a PDB that references debug
-      # information in .obj and .lib files instead of copying
-      # it all. This flag is incompatible with /PROFILE
-      ldflags = [ "/DEBUG:FASTLINK" ]
-    } else {
-      ldflags = [ "/DEBUG" ]
-    }
+# The BUILDCONFIG file sets the "default_symbols" config on targets by
+# default. It will be equivalent to one the three specific symbol levels.
+#
+# You can override the symbol level on a per-target basis by removing the
+# default config and then adding the named one you want:
+#
+#   configs -= [ "//build/config/compiler:default_symbols" ]
+#   configs += [ "//build/config/compiler:symbols" ]
+
+# Full symbols.
+if (is_win) {
+  import("//build/toolchain/goma.gni")
+  if (use_goma) {
+    symbols_cflags = [ "/Z7" ]  # No PDB file
   } else {
-    cflags = [ "-g2" ]
-    if (use_debug_fission) {
-      cflags += [ "-gsplit-dwarf" ]
-    }
+    symbols_cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
   }
+  if (is_win_fastlink) {
+    # Tell VS 2015+ to create a PDB that references debug
+    # information in .obj and .lib files instead of copying
+    # it all. This flag is incompatible with /PROFILE
+    symbols_ldflags = [ "/DEBUG:FASTLINK" ]
+  } else {
+    symbols_ldflags = [ "/DEBUG" ]
+  }
+} else {
+  symbols_cflags = [ "-g2" ]
+  if (use_debug_fission) {
+    symbols_cflags += [ "-gsplit-dwarf" ]
+  }
+  symbols_ldflags = []
+}
+
+config("symbols") {
+  cflags = symbols_cflags
+  ldflags = symbols_ldflags
+}
+
+# Minimal symbols.
+if (is_win) {
+  # Linker symbols for backtraces only.
+  minimal_symbols_cflags = []
+  if (is_win_fastlink) {
+    # Tell VS 2015+ to create a PDB that references debug
+    # information in .obj and .lib files instead of copying
+    # it all. This flag is incompatible with /PROFILE
+    minimal_symbols_ldflags = [ "/DEBUG:FASTLINK" ]
+  } else {
+    minimal_symbols_ldflags = [ "/DEBUG" ]
+  }
+} else {
+  minimal_symbols_cflags = [ "-g1" ]
+  if (use_debug_fission) {
+    minimal_symbols_cflags += [ "-gsplit-dwarf" ]
+  }
+  minimal_symbols_ldflags = []
 }
 
 config("minimal_symbols") {
-  if (is_win) {
-    # Linker symbols for backtraces only.
-    if (is_win_fastlink) {
-      # Tell VS 2015+ to create a PDB that references debug
-      # information in .obj and .lib files instead of copying
-      # it all. This flag is incompatible with /PROFILE
-      ldflags = [ "/DEBUG:FASTLINK" ]
-    } else {
-      ldflags = [ "/DEBUG" ]
-    }
-  } else {
-    cflags = [ "-g1" ]
-    if (use_debug_fission) {
-      cflags += [ "-gsplit-dwarf" ]
-    }
-  }
+  cflags = minimal_symbols_cflags
+  ldflags = minimal_symbols_ldflags
+}
+
+# No symbols.
+if (is_win) {
+  no_symbols_cflags = []
+} else {
+  no_symbols_cflags = [ "-g0" ]
 }
 
 config("no_symbols") {
-  if (!is_win) {
-    cflags = [ "-g0" ]
+  cflags = no_symbols_cflags
+}
+
+# Default symbols.
+config("default_symbols") {
+  if (symbol_level == 0) {
+    cflags = no_symbols_cflags
+  } else if (symbol_level == 1) {
+    cflags = minimal_symbols_cflags
+    ldflags = minimal_symbols_ldflags
+  } else if (symbol_level == 2) {
+    cflags = symbols_cflags
+    ldflags = symbols_ldflags
+  } else {
+    assert(false)
   }
 }
diff --git a/config/compiler/compiler.gni b/config/compiler/compiler.gni
new file mode 100644
index 000000000..d5db930da
--- /dev/null
+++ b/config/compiler/compiler.gni
@@ -0,0 +1,30 @@
+# Copyright 2015 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.
+
+import("//build/config/sanitizers/sanitizers.gni")
+
+declare_args() {
+  # How many symbols to include in the build. This affects the performance of
+  # the build since the symbols are large and dealing with them is slow.
+  #   2 means regular build with symbols.
+  #   1 means minimal symbols, usually enough for backtraces only.
+  #   0 means no symbols.
+  #   -1 means auto-set according to debug/release and platform.
+  symbol_level = -1
+}
+
+# If it wasn't manually set, set to an appropriate default.
+assert(symbol_level >= -1 && symbol_level <= 2, "Invalid symbol_level")
+if (symbol_level == -1) {
+  # Linux is slowed by having symbols as part of the target binary, whereas
+  # Mac and Windows have them separate, so in Release Linux, default them off.
+  if (is_debug || !is_linux) {
+    symbol_level = 2
+  } else if (is_asan || is_lsan || is_tsan || is_msan) {
+    # Sanitizers require symbols for filename suppressions to work.
+    symbol_level = 1
+  } else {
+    symbol_level = 0
+  }
+}
diff --git a/config/sanitizers/sanitizers.gni b/config/sanitizers/sanitizers.gni
index c575eb1cc..1aa212dea 100644
--- a/config/sanitizers/sanitizers.gni
+++ b/config/sanitizers/sanitizers.gni
@@ -3,6 +3,18 @@
 # found in the LICENSE file.
 
 declare_args() {
+  # Compile for Address Sanitizer to find memory bugs.
+  is_asan = false
+
+  # Compile for Leak Sanitizer to find leaks.
+  is_lsan = false
+
+  # Compile for Memory Sanitizer to find uninitialized reads.
+  is_msan = false
+
+  # Compile for Thread Sanitizer to find threading bugs.
+  is_tsan = false
+
   # Use libc++ (buildtools/third_party/libc++ and
   # buildtools/third_party/libc++abi) instead of stdlibc++ as standard library.
   # This is intended to be used for instrumented builds.
@@ -32,6 +44,12 @@ declare_args() {
   use_cfi_diag = false
 }
 
+# TODO(GYP) bug 527515: is_ubsan, is_ubsan_vptr
+using_sanitizer = is_asan || is_lsan || is_tsan || is_msan
+
+assert(!using_sanitizer || is_clang,
+       "Sanitizers (is_*san) require setting is_clang = true in 'gn args'")
+
 # MSan only links Chrome properly in release builds (brettw -- 9/1/2015). The
 # same is possibly true for the other non-ASan sanitizers. But regardless of
 # whether it links, one would normally never run a sanitizer in debug mode.
diff --git a/config/win/BUILD.gn b/config/win/BUILD.gn
index ba28c5ef7..e00c6d833 100644
--- a/config/win/BUILD.gn
+++ b/config/win/BUILD.gn
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/win/visual_studio_version.gni")
 
diff --git a/secondary/third_party/libjpeg_turbo/BUILD.gn b/secondary/third_party/libjpeg_turbo/BUILD.gn
index 4da2b7c27..6be39febb 100644
--- a/secondary/third_party/libjpeg_turbo/BUILD.gn
+++ b/secondary/third_party/libjpeg_turbo/BUILD.gn
@@ -5,6 +5,7 @@
 # Do not use the targets in this file unless you need a certain libjpeg
 # implementation. Use the meta target //third_party:jpeg instead.
 
+import("//build/config/sanitizers/sanitizers.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }