add timing info for flx creation

packages/flutter_tools/lib/src/commands/run.dart

@@ -123,7 +123,7 @@ class RunCommand extends RunCommandBase {
       debugPort: debugPort
     );
 
-    printTrace('Finished start command.');
+    printTrace('Finished $name command.');
     return result;
   }
 }

packages/flutter_tools/lib/src/flx.dart

@@ -256,7 +256,7 @@ Future<int> build(
 
 Future<int> assemble({
   Map manifestDescriptor: const {},
-  ArchiveFile snapshotFile: null,
+  ArchiveFile snapshotFile,
   String assetBasePath: defaultAssetBasePath,
   String materialAssetBasePath: defaultMaterialAssetBasePath,
   String outputPath: defaultFlxOutputPath,
@@ -287,11 +287,15 @@ Future<int> assemble({
   if (fontManifest != null)
     archive.addFile(fontManifest);
 
-  await CipherParameters.get().seedRandom();
+  printTrace('Calling CipherParameters.seedRandom().');
+  CipherParameters.get().seedRandom();
 
   AsymmetricKeyPair keyPair = keyPairFromPrivateKeyFileSync(privateKeyPath);
+  printTrace('KeyPair from $privateKeyPath: $keyPair.');
+  printTrace('Encoding zip file.');
   Uint8List zipBytes = new Uint8List.fromList(new ZipEncoder().encode(archive));
   ensureDirectoryExists(outputPath);
+  printTrace('Creating flx at ${outputPath}.');
   Bundle bundle = new Bundle.fromContent(
     path: outputPath,
     manifest: manifestDescriptor,

packages/flx/lib/bundle.dart

@@ -72,7 +72,7 @@ class Bundle {
     this.path,
     this.manifest,
     contentBytes,
-    AsymmetricKeyPair keyPair: null
+    AsymmetricKeyPair keyPair
   }) : _contentBytes = contentBytes {
     assert(path != null);
     assert(manifest != null);

packages/flx/lib/signing.dart

@@ -20,6 +20,7 @@ class CipherParameters {
   final String signerAlgorithm = 'SHA-256/ECDSA';
   final String hashAlgorithm = 'SHA-256';
   final ECDomainParameters domain = new ECDomainParameters('prime256v1');
+
   SecureRandom get random {
     if (_random == null)
       _initRandom(new Uint8List(16), new Uint8List(16));
@@ -29,12 +30,16 @@ class CipherParameters {
   // Seeds our secure random number generator using data from /dev/urandom.
   // Disclaimer: I don't really understand why we need 2 parameters for
   // pointycastle's API.
-  Future seedRandom() async {
+  void seedRandom() {
+    if (_random != null)
+      return;
+
     try {
-      RandomAccessFile file = await new File("/dev/urandom").open();
-      Uint8List key = new Uint8List.fromList(await file.read(16));
-      Uint8List iv = new Uint8List.fromList(await file.read(16));
+      RandomAccessFile file = new File("/dev/urandom").openSync();
+      Uint8List key = new Uint8List.fromList(file.readSync(16));
+      Uint8List iv = new Uint8List.fromList(file.readSync(16));
       _initRandom(key, iv);
+      file.closeSync();
     } on FileSystemException {
       // TODO(mpcomplete): need an entropy source on Windows. We might get this
       // for free from Dart itself soon.

packages/flx/test/signing_test.dart

@@ -34,7 +34,7 @@ main() async {
 
   // Set up a key generator.
   CipherParameters cipher = CipherParameters.get();
-  await cipher.seedRandom();
+  cipher.seedRandom();
   ECKeyGeneratorParameters ecParams = new ECKeyGeneratorParameters(cipher.domain);
   ParametersWithRandom<ECKeyGeneratorParameters> keyGeneratorParams =
     new ParametersWithRandom<ECKeyGeneratorParameters>(ecParams, cipher.random);