Add builders to APDU command class

device/u2f/u2f_apdu_command.h

Index: device/u2f/u2f_apdu_command.h
diff --git a/device/u2f/u2f_apdu_command.h b/device/u2f/u2f_apdu_command.h
index 06cd95e81cdf1c37c43cbc6ebfe55790a04e72c8..49f7cf2177bbb9de103fd7364d56df7f2b10bccf 100644
--- a/device/u2f/u2f_apdu_command.h
+++ b/device/u2f/u2f_apdu_command.h
@@ -37,6 +37,16 @@ class U2fApduCommand : public base::RefCountedThreadSafe<U2fApduCommand> {
   void set_response_length(size_t response_length) {
     response_length_ = response_length;
   }
+  static scoped_refptr<U2fApduCommand> BuildRegisterCommand(

[juanlang (chromium.org), 2017/01/28 00:08:39]

Maybe remove Command? The caller will be using
U2fApduCommand::BuildRegisterCommand, and I don't find repeating the word
Command all that valuable.

[Reilly Grant (use Gerrit), 2017/01/28 00:29:29]

I suggest U2fApduCommand::CreateRegister to match the methods above.

[Casey Piper, 2017/01/30 21:51:41]

Done.

[Casey Piper, 2017/01/30 21:51:41]

Acknowledged.

+      const std::vector<uint8_t>& appid_digest,
+      const std::vector<uint8_t>& challenge_digest);
+  static scoped_refptr<U2fApduCommand> BuildGetVersionCommand();

[juanlang (chromium.org), 2017/01/28 00:08:39]

Remove Get, it's cleaner that way.

[Casey Piper, 2017/01/30 21:51:41]

Done.

+  // Early U2F drafts defined a non-ISO 7816-4 conforming layout
+  static scoped_refptr<U2fApduCommand> BuildGetLegacyVersionCommand();

[juanlang (chromium.org), 2017/01/28 00:08:39]

Ditto.

[Casey Piper, 2017/01/30 21:51:41]

Done.

+  static scoped_refptr<U2fApduCommand> BuildSignCommand(
+      const std::vector<uint8_t>& appid_digest,
+      const std::vector<uint8_t>& challenge_digest,
+      const std::vector<uint8_t>& key_handle);
 
  private:
   friend class base::RefCountedThreadSafe<U2fApduCommand>;
@@ -44,6 +54,7 @@ class U2fApduCommand : public base::RefCountedThreadSafe<U2fApduCommand> {
   FRIEND_TEST_ALL_PREFIXES(U2fApduTest, TestDeserializeBasic);
   FRIEND_TEST_ALL_PREFIXES(U2fApduTest, TestDeserializeComplex);
   FRIEND_TEST_ALL_PREFIXES(U2fApduTest, TestSerializeEdgeCases);
+  FRIEND_TEST_ALL_PREFIXES(U2fApduTest, TestBuildApdu);
 
   static constexpr size_t kApduMinHeader = 4;
   static constexpr size_t kApduMaxHeader = 7;
@@ -55,6 +66,18 @@ class U2fApduCommand : public base::RefCountedThreadSafe<U2fApduCommand> {
   static constexpr size_t kApduMaxResponseLength = 65536;
   static constexpr size_t kApduMaxLength =
       kApduMaxDataLength + kApduMaxHeader + 2;
+  // APDU instructions
+  static constexpr uint8_t kInsU2fEnroll = 0x01;
+  static constexpr uint8_t kInsU2fSign = 0x02;
+  static constexpr uint8_t kInsU2fVersion = 0x03;
+  // P1 instructions
+  static constexpr uint8_t kP1TupRequired = 0x01;
+  static constexpr uint8_t kP1TupConsumed = 0x02;
+  static constexpr uint8_t kP1TupRequiredConsumed =
+      kP1TupRequired | kP1TupConsumed;
+  static constexpr size_t kMaxKeyHandleLength = 255;
+  static constexpr size_t kChallengeDigestLen = 32;
+  static constexpr size_t kAppIdDigestLen = 32;
 
   U2fApduCommand();
   U2fApduCommand(uint8_t cla,