Config changes to support target_os="fuchsia"

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index d055e705627c96782434537d0157594ff4f6dad0..9cd7a7797b2776acdd46c7d6450946dd52e11769 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -135,8 +135,9 @@ declare_args() {
 
   # Set to true when compiling with the Clang compiler. Typically this is used
   # to configure warnings.
-  is_clang = current_os == "mac" || current_os == "ios" ||
-             current_os == "linux" || current_os == "chromeos"
+  is_clang =
+      current_os == "mac" || current_os == "ios" || current_os == "linux" ||
+      current_os == "chromeos" || current_os == "fuchsia"
 
   # Allows the path to a custom target toolchain to be injected as a single
   # argument, and set as the default toolchain.
@@ -161,7 +162,8 @@ declare_args() {
   #
   # For more information see
   # https://chromium.googlesource.com/chromium/src/+/master/docs/component_build.md
-  is_component_build = is_debug && current_os != "ios"
+  is_component_build =
+      is_debug && current_os != "ios" && current_os != "fuchsia"
 }
 
 assert(!(is_debug && is_official_build), "Can't do official debug builds")
@@ -229,6 +231,8 @@ if (target_os == "android") {
   } else {
     _default_toolchain = "//build/toolchain/linux:$target_cpu"
   }
+} else if (target_os == "fuchsia") {
+  _default_toolchain = "//build/toolchain/fuchsia:$target_cpu"
 } else if (target_os == "ios") {
   _default_toolchain = "//build/toolchain/mac:ios_clang_$target_cpu"
 } else if (target_os == "mac") {
@@ -279,6 +283,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
     current_os == "winrt_81_phone" || current_os == "winrt_10") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
   is_ios = false
   is_linux = false
   is_mac = false
@@ -288,6 +293,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
 } else if (current_os == "mac") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
   is_ios = false
   is_linux = false
   is_mac = true
@@ -297,6 +303,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
 } else if (current_os == "android") {
   is_android = true
   is_chromeos = false
+  is_fuchsia = false
   is_ios = false
   is_linux = false
   is_mac = false
@@ -306,6 +313,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
 } else if (current_os == "chromeos") {
   is_android = false
   is_chromeos = true
+  is_fuchsia = false
   is_ios = false
   is_linux = true
   is_mac = false
@@ -318,15 +326,27 @@ if (current_os == "win" || current_os == "winrt_81" ||
   # Posix variant.
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
   is_ios = false
   is_linux = false
   is_mac = false
   is_nacl = true
   is_posix = true
   is_win = false
+} else if (current_os == "fuchsia") {
+  is_android = false
+  is_chromeos = false
+  is_fuchsia = true
+  is_ios = false
+  is_linux = false
+  is_mac = false
+  is_nacl = false
+  is_posix = true
+  is_win = false
 } else if (current_os == "ios") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
   is_ios = true
   is_linux = false
   is_mac = false
@@ -336,6 +356,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
 } else if (current_os == "linux") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
   is_ios = false
   is_linux = true
   is_mac = false