libchrome: Uprev the library to r456626 from Chromium

Pulled the latest and greatest version of libchrome from Chromium.

The merge was done against r456626 which corresponds to git commit
08266b3fca707804065a2cfd60331722ade41969 of Mar 14, 2017

Notable changes are:
- FOR_EACH_OBSERVER macro removed (replaced by use of C++ 11
  range-base for loop)
- base::Values no more FundamentalValue
- stl_util moved to base namespace
- some scoped pointers removed in crypto/ in favor
  of BoringSSL UniquePtr.
- path() accessor renamed to GetPath() in ScopedTempDir (and other
  classes)
- introduction of base::CallbackOnce

Test: All unit-tests should still pass.

Change-Id: I5c2cb41ea4c037fe69fbb425e711b1399d55d591
585 files changed