Work on GN toolchain definitions and build

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index dd1d2764896a719fb3a6d55089263823aa8c56b4..f3d86fc37f647a9defd954602d72f647a3219fd0 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -118,7 +118,7 @@ if (os == "win") {
     is_clang = true  # Always use clang on Mac.
   }
 } else if (os == "android") {
-  is_android = false
+  is_android = true
   is_chromeos = false
   is_ios = false
   is_linux = true
@@ -413,6 +413,8 @@ set_defaults("source_set") {
 # default toolchain.
 
 if (is_win) {
+  # TODO(brettw) name the toolchains the same as cpu_arch as with Linux below
+  # to eliminate these conditionals.
   if (build_cpu_arch == "x64") {
     host_toolchain = "//build/toolchain/win:64"
   } else if (build_cpu_arch == "x86") {
@@ -424,22 +426,12 @@ if (is_win) {
   } else if (cpu_arch == "x86") {
     set_default_toolchain("//build/toolchain/win:32")
   }
+} else if (is_android) {
+  host_toolchain = "//build/toolchain/linux:$build_cpu_arch"
+  set_default_toolchain("//build/toolchain/android:$cpu_arch")
 } else if (is_linux) {
-  if (build_cpu_arch == "arm") {
-    host_toolchain = "//build/toolchain/linux:arm"
-  } else if (build_cpu_arch == "x86") {
-    host_toolchain = "//build/toolchain/linux:32"
-  } else if (build_cpu_arch == "x64") {
-    host_toolchain = "//build/toolchain/linux:64"
-  }
-
-  if (build_cpu_arch == "arm") {
-    set_default_toolchain("//build/toolchain/linux:arm")
-  } else if (build_cpu_arch == "x86") {
-    set_default_toolchain("//build/toolchain/linux:32")
-  } else if (build_cpu_arch == "x64") {
-    set_default_toolchain("//build/toolchain/linux:64")
-  }
+  host_toolchain = "//build/toolchain/linux:$build_cpu_arch"
+  set_default_toolchain("//build/toolchain/linux:$cpu_arch")
 } else if (is_mac || is_ios) {
   host_toolchain = "//build/toolchain/mac:clang"
   set_default_toolchain(host_toolchain)