PPAPI: Make CallWhileUnlocked more permissive.

PPAPI: Make CallWhileUnlocked more permissive.

Prior to this patch, CallWhileUnlocked required its parameters' types to
be perfect matches to the types in the function pointer it's meant to
invoke. This is counter to programmers' usual expectations for function
calls, since the compiler will usually do safe casts like add const or
promoting integral types. This just adds template params to CallWhileUnlocked
so that any call with the appropriate number of parameters will be a template
match. The compiler will still decide if there is a valid implicit conversion,
so this is still safe in the sense that mismatched params still won't
compile.

BUG=160925
Committed: https://crrev.com/36e91cd9ac1516a202ab09cc5ea98781c84db0d8
Cr-Commit-Position: refs/heads/master@{#294405}

[dmichael (off chromium), 2014-09-11 15:58:32]

dmichael@chromium.org changed reviewers:
+ teravest@chromium.org

[teravest, 2014-09-11 16:06:50]

lgtm

This is much better.

[dmichael (off chromium), 2014-09-11 16:08:13]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-09-11 16:09:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/552423003/1

[commit-bot: I haz the power, 2014-09-11 16:58:45]

Committed patchset #1 (id:1) as 106d4fdf5be4870bdf4da596137694c011b03f86

[commit-bot: I haz the power, 2014-09-11 17:03:41]

Patchset 1 (id:??) landed as
https://crrev.com/36e91cd9ac1516a202ab09cc5ea98781c84db0d8
Cr-Commit-Position: refs/heads/master@{#294405}