[grpc] Moved windows builds to use static builds.

Flow for windows based shared object is different. Currently no need to
have grpc build as a library on windows. Moving it to a regular static
build.

Bug: 1152807
Test: CQ
Change-Id: I1436b85411618a72edd69e382f06a53267fdb69d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566718
Commit-Queue: Andres Medina <medinaandres@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Auto-Submit: Andres Medina <medinaandres@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832377}

third_party/grpc/BUILD.gn

@@ -78,7 +78,8 @@ config("grpc_config_private") {
 template("grpc_so") {
   # TODO(169395837): Somehow gRPC symbols cannot be found on Android.
   # Keep using static linking for now.
-  if (is_android) {
+  # In windows use static linking.
+  if (is_android || is_win) {
     source_set(target_name) {
       forward_variables_from(invoker, "*")
     }

third_party/grpc/template/BUILD.chromium.gn.template

@@ -83,7 +83,8 @@
   template("grpc_so") {
     # TODO(169395837): Somehow gRPC symbols cannot be found on Android.
     # Keep using static linking for now.
-    if (is_android) {
+    # In windows use static linking.
+    if (is_android || is_win) {
       source_set(target_name) {
         forward_variables_from(invoker, "*")
       }