Fix the WinAsan dependency to thunk dll.

build/toolchain/win/BUILD.gn

Index: build/toolchain/win/BUILD.gn
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index 7d0b7d232f5237184d1aedd2577c075e502745fc..396af247e5e16e37553d0d64aabe149f6ecee5b1 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -285,6 +285,9 @@ template("msvc_toolchain") {
       if (defined(invoker.is_component_build)) {
         is_component_build = invoker.is_component_build
       }
+      if (defined(invoker.is_asan)) {
+        is_asan = invoker.is_asan
+      }
 
       # This value needs to be passed through unchanged.
       host_toolchain = host_toolchain
@@ -369,6 +372,9 @@ template("win_x64_toolchains") {
     if (defined(invoker.is_component_build)) {
       is_component_build = invoker.is_component_build
     }
+    if (defined(invoker.is_asan)) {
+      is_asan = invoker.is_asan
+    }
   }
 
   msvc_toolchain("clang_" + target_name) {
@@ -385,6 +391,9 @@ template("win_x64_toolchains") {
     if (defined(invoker.is_component_build)) {
       is_component_build = invoker.is_component_build
     }
+    if (defined(invoker.is_asan)) {
+      is_asan = invoker.is_asan
+    }
   }
 }
 
@@ -394,6 +403,9 @@ win_x64_toolchains("x64") {
   concurrent_links = concurrent_links
   goma_prefix = goma_prefix
   x64_toolchain_data = x64_toolchain_data
+  if (target_cpu == "x86") {
+    is_asan = false
+  }
 }
 
 # The nacl_win64 toolchain is nearly identical to the plain x64 toolchain.
@@ -403,6 +415,7 @@ win_x64_toolchains("x64") {
 # building nacl64.exe in component style does not work.
 win_x64_toolchains("nacl_win64") {
   is_component_build = false
+  is_asan = false
 
   # TODO(mcgrathr): These assignments are only required because of
   # crbug.com/395883.  Drop them if that ever gets fixed in GN.