Fix sky build on android

sky/engine/platform/BUILD.gn

 # Copyright 2014 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/ui.gni")
 import("//sky/engine/build/scripts/scripts.gni")
 import("//sky/engine/config.gni")
-import("//third_party/yasm/yasm_assemble.gni")
 
 # Most targets in this file are private actions so use that as the default.
 visibility = [":*"]
 
 sky_platform_output_dir = "$root_gen_dir/sky/platform"
 
 component("sky_common") {
   visibility += ["//sky/*"]
   sources = [
     "exported/WebCString.cpp",
@@ skipping 728 matching lines @@
 
   if (is_linux) {
     direct_dependent_configs = [ "//build/config/linux:fontconfig" ]
   }
 
   if (cpu_arch == "arm") {
     deps += [ ":sky_arm_neon" ]
   }
 }
 
+if (cpu_arch == "x86" || cpu_arch == "x64") {
+
+import("//third_party/yasm/yasm_assemble.gni")
+
 yasm_assemble("heap_asm_stubs") {
-  if (cpu_arch == "x86" || cpu_arch == "x64") {
-    sources = [ "heap/asm/SaveRegisters_x86.asm" ]
-  } else if (cpu_arch == "arm") {
-    sources = [ "heap/asm/SaveRegisters_arm.S" ]
-  } else if (cpu_arch == "arm64") {
-    sources = [ "heap/asm/SaveRegisters_arm64.S" ]
-  } else if (cpu_arch == "mipsel") {
-    sources = [ "heap/asm/SaveRegisters_mips.S" ]
-  }
+  sources = [ "heap/asm/SaveRegisters_x86.asm" ]
 
   yasm_flags = []
   if (is_mac) {
     # Necessary to ensure symbols end up with a _ prefix; added by
     # yasm_compile.gypi for Windows, but not Mac.
     yasm_flags += [ "-DPREFIX" ]
   }
   if (cpu_arch == "x64") {
     if (is_win) {
       yasm_flags += [ "-DX64WIN=1" ]
     } else {
       yasm_flags += [ "-DX64POSIX=1" ]
     }
   } else if (cpu_arch == "x86") {
     yasm_flags += [ "-DIA32=1" ]
-  } else if (cpu_arch == "arm") {
-    yasm_flags += [ "-DARM=1" ]
   }
 }
 
+} else { # cpu_arch == "x86" || cpu_arch == "x64"
+
+source_set("heap_asm_stubs") {
+  if (cpu_arch == "arm") {
+    sources = [ "heap/asm/SaveRegisters_arm.S" ]
+  } else if (cpu_arch == "arm64") {
+    sources = [ "heap/asm/SaveRegisters_arm64.S" ]
+  } else if (cpu_arch == "mipsel") {
+    sources = [ "heap/asm/SaveRegisters_mips.S" ]
+  }
+
+  if (cpu_arch == "arm") {
+    defines = [ "ARM=1" ]
+  }
+}
+
+}
+
 test("platform_unittests") {
   visibility += ["//sky/*"]
   output_name = "sky_platform_unittests"
 
   sources = [
     "ClockTest.cpp",
     "DecimalTest.cpp",
     "LayoutUnitTest.cpp",
     "LifecycleContextTest.cpp",
     "PODArenaTest.cpp",
@@ skipping 86 matching lines @@
     #'cflags': ['-marm'],
     #    'conditions': [
     #      ['OS=="android"', {
     #        'cflags!': ['-mthumb'],
     #      }],
     #    ],
 
     deps = [ ":sky_common" ]
   }
 }