Wire up the stub native resolver for all libraries in gen_snapshot

Fixes https://github.com/flutter/flutter/issues/6952

BUG=
R=rmacnak@google.com

Review URL: https://codereview.chromium.org/2518233003 .

runtime/bin/gen_snapshot.cc

@@ -22,6 +22,7 @@
 #include "bin/vmservice_impl.h"
 
 #include "include/dart_api.h"
+#include "include/dart_tools_api.h"
 
 #include "platform/hashmap.h"
 #include "platform/globals.h"
@@ -684,7 +685,8 @@ static const char StubNativeFunctionName[] = "StubNativeFunction";
 
 void StubNativeFunction(Dart_NativeArguments arguments) {
   // This is a stub function for the resolver
-  UNREACHABLE();
+  Dart_SetReturnValue(
+      arguments, Dart_NewApiError("<EMBEDDER DID NOT SETUP NATIVE RESOLVER>"));
 }
 
 
@@ -735,6 +737,31 @@ static void SetupStubNativeResolver(size_t lib_index,
 }
 
 
+// Iterate over all libraries and setup the stub native lookup. This must be
+// run after |SetupStubNativeResolversForPrecompilation| because the former
+// loads some libraries.
+static void SetupStubNativeResolvers() {
+  Dart_Handle library_ids = Dart_GetLibraryIds();
+  intptr_t library_ids_length;
+  Dart_ListLength(library_ids, &library_ids_length);
+  for (intptr_t i = 0; i < library_ids_length; i++) {
+    Dart_Handle library_id_handle = Dart_ListGetAt(library_ids, i);
+    DART_CHECK_VALID(library_id_handle);
+    int64_t library_id;
+    Dart_IntegerToInt64(library_id_handle, &library_id);
+    Dart_Handle library = Dart_GetLibraryFromId(library_id);
+    DART_CHECK_VALID(library);
+    Dart_NativeEntryResolver old_resolver = NULL;
+    Dart_GetNativeResolver(library, &old_resolver);
+    if (old_resolver == NULL) {
+      Dart_Handle result =
+          Dart_SetNativeResolver(library, &StubNativeLookup, &StubNativeSymbol);
+      DART_CHECK_VALID(result);
+    }
+  }
+}
+
+
 static void ImportNativeEntryPointLibrariesIntoRoot(
     const Dart_QualifiedFunctionName* entries) {
   if (entries == NULL) {
@@ -1306,6 +1333,8 @@ int main(int argc, char** argv) {
 
     SetupStubNativeResolversForPrecompilation(entry_points);
 
+    SetupStubNativeResolvers();
+
     if (!is_kernel_file) {
       // Load the specified script.
       library = LoadSnapshotCreationScript(app_script_name);

runtime/include/dart_api.h

@@ -2703,6 +2703,30 @@ Dart_SetNativeResolver(Dart_Handle library,
 /* TODO(turnidge): Rename to Dart_LibrarySetNativeResolver? */
 
 
+/**
+ * Returns the callback used to resolve native functions for a library.
+ *
+ * \param library A library.
+ * \param resolver a pointer to a Dart_NativeEntryResolver
+ *
+ * \return A valid handle if the library was found.
+ */
+DART_EXPORT Dart_Handle
+Dart_GetNativeResolver(Dart_Handle library, Dart_NativeEntryResolver* resolver);
+
+
+/**
+ * Returns the callback used to resolve native function symbols for a library.
+ *
+ * \param library A library.
+ * \param resolver a pointer to a Dart_NativeEntrySymbol.
+ *
+ * \return A valid handle if the library was found.
+ */
+DART_EXPORT Dart_Handle Dart_GetNativeSymbol(Dart_Handle library,
+                                             Dart_NativeEntrySymbol* resolver);
+
+
 /*
  * =====================
  * Scripts and Libraries

runtime/vm/dart_api_impl.cc

@@ -5865,6 +5865,32 @@ Dart_SetNativeResolver(Dart_Handle library,
 }
 
 
+DART_EXPORT Dart_Handle
+Dart_GetNativeResolver(Dart_Handle library,
+                       Dart_NativeEntryResolver* resolver) {
+  *resolver = NULL;
+  DARTSCOPE(Thread::Current());
+  const Library& lib = Api::UnwrapLibraryHandle(Z, library);
+  if (lib.IsNull()) {
+    RETURN_TYPE_ERROR(Z, library, Library);
+  }
+  *resolver = lib.native_entry_resolver();
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_GetNativeSymbol(Dart_Handle library,
+                                             Dart_NativeEntrySymbol* resolver) {
+  *resolver = NULL;
+  DARTSCOPE(Thread::Current());
+  const Library& lib = Api::UnwrapLibraryHandle(Z, library);
+  if (lib.IsNull()) {
+    RETURN_TYPE_ERROR(Z, library, Library);
+  }
+  *resolver = lib.native_entry_symbol_resolver();
+  return Api::Success();
+}
+
 // --- Peer support ---
 
 DART_EXPORT Dart_Handle Dart_GetPeer(Dart_Handle object, void** peer) {