UMA: Add WebCore.WebSocket.SendType

UMA: Add WebCore.WebSocket.SendType

Corresponds to Blink change https://codereview.chromium.org/244923002/.
Used to study:
- how many send() calls are being made
- how much binary data sending functionality is used
- how many people are using ArrayBufferView version send()

BUG=128156, 359926
R=asvitkine@chromium.org, ricea@chromium.org, yhirano@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=266143

[Adam Rice, 2014-04-22 03:56:52]

https://codereview.chromium.org/246573002/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/246573002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:29747: +    Count the number of send()
method call on WebSockets for each argument type.
s/call/calls/

[tyoshino (SeeGerritForStatus), 2014-04-22 04:11:42]

https://codereview.chromium.org/246573002/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/246573002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:29747: +    Count the number of send()
method call on WebSockets for each argument type.
On 2014/04/22 03:56:52, Adam Rice wrote:
> s/call/calls/

Done.

[Adam Rice, 2014-04-22 04:21:54]

lgtm

[yhirano, 2014-04-22 08:26:37]

lgtm

[tyoshino (SeeGerritForStatus), 2014-04-23 03:53:51]

+asvitkine for histograms.xml

[Alexei Svitkine (slow), 2014-04-23 13:19:57]

lgtm

[tyoshino (SeeGerritForStatus), 2014-04-25 06:17:37]

Committed patchset #4 manually as r266143 (presubmit successful).