Changing the behavior of ReleaseSession() from Close() to Remove()

Merge 291602 "Changing the behavior of ReleaseSession() from Close() to Remove()"

With the recent EME spec changes, ReleaseSession() got replaced by
CloseSession() and RemoveSession(). Until all the changes to support
both methods are in place, calls to ReleaseSession() should call
RemoveSession() in order for existing prefixed EME applications
to continue to work.

Unprefixed Close() calls now call RemoveSession(), and thus don't do
the correct thing. This will be fixed when both CloseSession() and
RemoveSession() are passed through Pepper.

BUG=406606
TEST=All EME browser_tests pass

Review URL: https://codereview.chromium.org/497153005

Cr-Commit-Position: refs/heads/master@{#291602}
(cherry picked from commit ec6d38eaaacd81198e1a78dec84418b54b218e55)

R=xhwang@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/baa7b336638b4d8e85ad86ece54b80a13a5c819c

[jrummell, 2014-09-02 23:53:22]

jrummell@chromium.org changed reviewers:
+ xhwang@chromium.org

[jrummell, 2014-09-02 23:53:23]

This was reviewed as https://codereview.chromium.org/497153005, just merging the
change into M38.

[xhwang, 2014-09-02 23:58:44]

I don't know what the new rule is for merge CLs, but drover used to generate a
title as the following before:

Merge 123456 "Old CL Title."

Does it make sense to use the same style?

otherwise, lgtm

[jrummell, 2014-09-03 00:28:32]

Committed patchset #1 (id:1) manually as baa7b33 (presubmit successful).