Web MIDI: enable midi_host.cc implementation on Android

content/browser/renderer_host/media/midi_host.cc

Index: content/browser/renderer_host/media/midi_host.cc
diff --git a/content/browser/renderer_host/media/midi_host.cc b/content/browser/renderer_host/media/midi_host.cc
index 6ed473afeff10538ef4ee2b8fb7db5ce3b5beccb..d059916514318a5b0f325122caa98c24e2825b08 100644
--- a/content/browser/renderer_host/media/midi_host.cc
+++ b/content/browser/renderer_host/media/midi_host.cc
@@ -110,17 +110,12 @@ void MIDIHost::OnSendData(int port,
   if (data.size() > 0 && data[0] >= kSysExMessage)
       return;
 
-#if defined(OS_ANDROID)
-  // TODO(toyoshim): figure out why data() method does not compile on Android.

[scherkus (not reviewing), 2013/08/19 17:28:20]

AFAIK data() is part of C++11 :)

[Takashi Toyoshima, 2013/08/19 18:03:40]

Agreed. http://www.cplusplus.com/reference/vector/vector/

-  NOTIMPLEMENTED();
-#else
   midi_manager_->DispatchSendMIDIData(
       this,
       port,
-      data.data(),
+      &data.front(),

[scherkus (not reviewing), 2013/08/19 17:28:20]

FYI technically this would segfault calling front() if data was empty, but in my
local test program &data.front() returns a null pointer whereas data.front()
segfaults

stepping back a bit ... do you need to call this method if data is empty?
perhaps you can return earlier in the method?

[Takashi Toyoshima, 2013/08/19 18:03:40]

Oh, I didn't think empty cases.
Actually, a renderer execute send operation only if length > 0.
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...
But this runs in browser process. We should not trust renderers here.
I'll add size check.

       data.size(),
       timestamp);
-#endif
 
   sent_bytes_in_flight_ += data.size();
 }