[Cast Extensions] Update dependencies to use non-generated target names

Update some cast dependencies to use the target name from the BUILD.gn
file, rather than the generated target name. This is clearer, since
these targets are specified within the BUILD.gn file at the location,
and also removes one duplicate target dependency.

Also prevent targets from depending on the generated target names by
restricting their visibility to the output static library.

Bug: None
Change-Id: Ib87f2d90edab44e52569e29b6c1675238df6efdc
Reviewed-on: https://chromium-review.googlesource.com/1150935Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578478}

chromecast/browser/BUILD.gn

@@ -305,8 +305,8 @@ cast_source_set("browser") {
     }
 
     deps += [
-      "//chromecast/common/extensions_api:api_registration_bundle_generator_registration",
-      "//chromecast/common/extensions_api:api_schema_generator",
+      "//chromecast/common/extensions_api:api",
+      "//chromecast/common/extensions_api:api_registration",
       "//components/guest_view/browser",
       "//components/keyed_service/content",
       "//components/pref_registry",

chromecast/common/BUILD.gn

@@ -43,12 +43,11 @@ cast_source_set("common") {
     deps += [
       "//chromecast/common/extensions_api:api",
       "//chromecast/common/extensions_api:api_registration",
-      "//chromecast/common/extensions_api:api_schema_generator",
       "//chromecast/common/extensions_api:extensions_features",
       "//components/version_info",
       "//extensions:extensions_resources_grd_grit",
       "//extensions/common",
-      "//extensions/common/api:generated_api_bundle_generator_schema",
+      "//extensions/common/api:generated_api",
       "//extensions/shell:resources",
       "//extensions/shell:resources_grit",
     ]

tools/json_schema_compiler/json_schema_api.gni

@@ -102,9 +102,15 @@ template("json_schema_api") {
 
   root_namespace = invoker.root_namespace
 
+  # Save the target_name, since other targets (like the action() and
+  # action_foreach() below) need to reference them, but would have their own
+  # target_name variable.
+  root_target_name = target_name
+
   if (schemas) {
     schema_generator_name = target_name + "_schema_generator"
     action_foreach(schema_generator_name) {
+      visibility = [":$root_target_name"]
       script = compiler_script
       sources = invoker.sources
       inputs = compiler_sources
@@ -140,6 +146,7 @@ template("json_schema_api") {
 
     bundle_generator_schema_name = target_name + "_bundle_generator_schema"
     action(bundle_generator_schema_name) {
+      visibility = [":$root_target_name"]
       script = compiler_script
       inputs = compiler_sources + invoker.sources + uncompiled_sources +
                uncompiled_bundle_schema_sources
@@ -178,6 +185,7 @@ template("json_schema_api") {
     bundle_generator_registration_name =
         target_name + "_bundle_generator_registration"
     action(bundle_generator_registration_name) {
+      visibility = [":$root_target_name"]
       script = compiler_script
       inputs = compiler_sources + invoker.sources + uncompiled_sources
       outputs = [