Web MIDI: use GetVendorName() result only if it is available

Web MIDI: use GetVendorName() result only if it is available

Since some minor devices are not supported by GetVendorName(),
do not return immediately, but continue to do the next trial
to find out the vendor name.

BUG=474245
Committed: https://crrev.com/b8e1ec5458f7097b84a89babf8208223117573ed
Cr-Commit-Position: refs/heads/master@{#323926}

[Takashi Toyoshima, 2015-04-06 17:10:35]

toyoshim@chromium.org changed reviewers:
+ yukawa@chromium.org

[Takashi Toyoshima, 2015-04-06 17:10:55]

See the bug, and PTAL.

[yukawa, 2015-04-06 17:24:55]

Thank you for catching this.

https://codereview.chromium.org/1061893002/diff/1/media/midi/midi_manager_win.cc
File media/midi/midi_manager_win.cc (right):

https://codereview.chromium.org/1061893002/diff/1/media/midi/midi_manager_win...
media/midi/midi_manager_win.cc:296: if (name)
Probably
  return std::string(name ? name : "");
might be better because |info.manufacturer_id| is almost always the same value
when |info.is_usb_device| is true, and the actual value of 
|info.manufacturer_id| is probably useless for us to distinguish device
manufacture.

Another idea is to use StringPiece, which is NULL-tolerant.

base::StringPiece GetManufacturerName(const MidiDeviceInfo& info) {
  if (info.is_usb_device) {
    // Note: |base::StringPiece| can be constructed even from nullptr.
    return device::UsbIds::GetVendorName(info.usb_vendor_id);
  }
  ....
}

[Takashi Toyoshima, 2015-04-06 17:46:46]

Since each USB device contains a manufacturer string by itself, I guess there is
another way to obtain the string via Windows API, and that was the reason why I
would not give up here.
For USB storage devices, there is a way;
http://stackoverflow.com/questions/7138361/manufacturer-string-and-product-st....

But, for now, it's ok to use name ? name : "".

[Takashi Toyoshima, 2015-04-06 17:49:48]

PTAL patch set 2.

[yukawa, 2015-04-06 17:53:14]

lgtm

[yukawa, 2015-04-06 17:53:17]

The CQ bit was checked by yukawa@chromium.org

[commit-bot: I haz the power, 2015-04-06 17:53:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1061893002/20001

[commit-bot: I haz the power, 2015-04-06 18:55:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-06 18:56:10]

Patchset 2 (id:??) landed as
https://crrev.com/b8e1ec5458f7097b84a89babf8208223117573ed
Cr-Commit-Position: refs/heads/master@{#323926}