Pepper: Cleanup in PepperReverseInterface.

Some code in PepperReverseInterface is more complicated than it needs to be.
I figured I'd clean this up a bit while I was looking at the manifest handling
logic.

BUG=
R=dmichael@chromium.org

Review URL: https://codereview.chromium.org/183793007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255425 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255425
Remove default values for custom CDM component manifest properties.

Versions that manifests without these values are no longer supported.

BUG=314162
TEST=Manually verified that the CDM still works using a manifest from M33.
R=sorin@chromium.org, xhwang@chromium.org

Review URL: https://codereview.chromium.org/180953006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255426 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255426