Add PDFiumEngineExportsTest.

Add test cases for GetPDFDocInfo() and GetPDFPageSizeByIndex(). Since
these tests exercise PDFium with V8 enabled, there needs to be
additional calls to code in gin/v8_initializer.h.

Change-Id: I24e2ed21b850a7e1fb65ebb0c0c8948447641710
Reviewed-on: https://chromium-review.googlesource.com/1136015
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575409}
3 files changed