Revert of PPAPI: Make GetProxiedInterface not re-enter the plugin (patchset #2 id:20001 of https://codereview.chromium.org/704913002/)

Reason for revert:
reverted due to 431529

Original issue's description:
> PPAPI: Make GetProxiedInterface not re-enter the plugin
>
> It's important that we never re-enter the plugin when it is blocked on
> synchronous calls to the renderer (unless they are scripting messages, which
> have to be re-entrant). This especially breaks assumptions in OpenGL usage.
>
> This required making the plugin side of the PPB_VideoDecoder_Dev proxy check
> for the interface prior to sending its synchronous Create message. I audited
> all the other uses of GetProxiedInterface from the renderer, and none of the
> others happen as a result of a sync plugin->renderer message.
>
> I also renamed the existing "SupportsInterface" message to "IsInterfaceSupported" to make the intent more obvious, and because I liked the SupportsInterface name better for the new usage: Telling the renderer that an interface is supported.
>
> BUG=418651
>
> Committed: https://crrev.com/a17de8faa97ca33d1e58e08392dbdc3e316d6cbe
> Cr-Commit-Position: refs/heads/master@{#303247}

[email protected],[email protected],[email protected],[email protected]
NOTREECHECKS=true
NOTRY=true
BUG=418651

Review URL: https://codereview.chromium.org/714483002

Cr-Commit-Position: refs/heads/master@{#303388}
9 files changed