Revert "Revert "GN: define SK_XML to indicate :xml is enabled.""

This reverts commit 7e8f80a08444f534376a25d45194c92f948c9594.

Reason for revert: the SVG DM flakiness should be fixed by now.

Original change's description:
> Revert "GN: define SK_XML to indicate :xml is enabled."
> 
> This reverts commit 7234448c11b0493a072723acd185dae986103df6.
> 
> Reason for revert: this enabled tests which are making the bots flaky.
> 
> Original change's description:
> > GN: define SK_XML to indicate :xml is enabled.
> > 
> > Without this, nothing ever defines SK_XML for dm/DM.cpp, dm/DMSrcSink.cpp, tests/SkDOMTest.cpp or tests/SkPEGTest.cpp.
> > 
> > GYP does something similiar in gyp/xml.gyp.
> > 
> > BUG=skia:
> > 
> > GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4500
> > 
> > Change-Id: I93322722d6d86f5802495d7a2edad2f82ba36f69
> > Reviewed-on: https://skia-review.googlesource.com/4500
> > Reviewed-by: Hal Canary <halcanary@google.com>
> > Commit-Queue: Eric Boren <borenet@google.com>
> > Commit-Queue: Mike Klein <mtklein@chromium.org>
> > 
> 
> TBR=mtklein@chromium.org,borenet@google.com,halcanary@google.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> 
> Change-Id: I46c198f4985f6e7f96c07b3100a3877ba46fdb18
> Reviewed-on: https://skia-review.googlesource.com/4526
> Commit-Queue: Mike Klein <mtklein@chromium.org>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> 

TBR=mtklein@chromium.org,borenet@google.com,halcanary@google.com,fmalita@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Ic3225f119dff3c6949a3b559ac60707d36bc3792
Reviewed-on: https://skia-review.googlesource.com/4544
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index f089dc5747..4ffbb01b39 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -501,6 +501,7 @@ optional("webp") {
 
 optional("xml") {
   enabled = skia_use_expat
+  public_defines = [ "SK_XML" ]
 
   deps = [
     "//third_party/expat",