Allow most third_party targets to use system libraries if asked.

This extends the pattern in freetype2 to expat, icu, libjpeg-turbo, libpng, libwebp, and zlib, and gives all these an arg to control which to use.

Homebrew doesn't have dng_sdk, piex, or sftnly, or I'd have done the same for them too.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4260

DOCS_PREVIEW= https://skia.org/?cl=4260

Change-Id: I82e780502bf2217336e791787f172a6fc8f55460
Reviewed-on: https://skia-review.googlesource.com/4260
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Hal Canary <halcanary@google.com>

1 files changed, 121 insertions, 111 deletions

diff --git a/third_party/libwebp/BUILD.gn b/third_party/libwebp/BUILD.gn
index ec51cd3b38..e7dc336534 100644
--- a/third_party/libwebp/BUILD.gn
+++ b/third_party/libwebp/BUILD.gn
@@ -4,123 +4,133 @@
 # found in the LICENSE file.
 
 declare_args() {
+  skia_use_system_libwebp = false
 }
 
 import("../third_party.gni")
 
-third_party("libwebp") {
-  public_include_dirs = [ "../externals/libwebp/src" ]
-
-  if (is_android) {
-    deps = [
-      "//third_party/cpu-features",
+if (skia_use_system_libwebp) {
+  system("libwebp") {
+    libs = [
+      "webp",
+      "webpdemux",
     ]
   }
+} else {
+  third_party("libwebp") {
+    public_include_dirs = [ "../externals/libwebp/src" ]
+
+    if (is_android) {
+      deps = [
+        "//third_party/cpu-features",
+      ]
+    }
 
-  defines = [
-    # WebP naturally decodes to RGB_565, and we work with BGR_565.
-    # This makes WebP decode to BGR_565 when we ask for RGB_565.
-    # (It also swaps the color order for 4444, but we don't care today.)
-    # TODO: swizzle ourself in SkWebpCodec instead of requiring this non-standard libwebp.
-    "WEBP_SWAP_16BIT_CSP",
-  ]
+    defines = [
+      # WebP naturally decodes to RGB_565, and we work with BGR_565.
+      # This makes WebP decode to BGR_565 when we ask for RGB_565.
+      # (It also swaps the color order for 4444, but we don't care today.)
+      # TODO: swizzle ourself in SkWebpCodec instead of requiring this non-standard libwebp.
+      "WEBP_SWAP_16BIT_CSP",
+    ]
 
-  sources = [
-    "../externals/libwebp/src/dec/alpha.c",
-    "../externals/libwebp/src/dec/buffer.c",
-    "../externals/libwebp/src/dec/frame.c",
-    "../externals/libwebp/src/dec/idec.c",
-    "../externals/libwebp/src/dec/io.c",
-    "../externals/libwebp/src/dec/quant.c",
-    "../externals/libwebp/src/dec/tree.c",
-    "../externals/libwebp/src/dec/vp8.c",
-    "../externals/libwebp/src/dec/vp8l.c",
-    "../externals/libwebp/src/dec/webp.c",
-    "../externals/libwebp/src/demux/demux.c",
-    "../externals/libwebp/src/dsp/alpha_processing.c",
-    "../externals/libwebp/src/dsp/alpha_processing_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/alpha_processing_sse2.c",
-    "../externals/libwebp/src/dsp/alpha_processing_sse41.c",
-    "../externals/libwebp/src/dsp/argb.c",
-    "../externals/libwebp/src/dsp/argb_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/argb_sse2.c",
-    "../externals/libwebp/src/dsp/cost.c",
-    "../externals/libwebp/src/dsp/cost_mips32.c",
-    "../externals/libwebp/src/dsp/cost_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/cost_sse2.c",
-    "../externals/libwebp/src/dsp/cpu.c",
-    "../externals/libwebp/src/dsp/dec.c",
-    "../externals/libwebp/src/dsp/dec_clip_tables.c",
-    "../externals/libwebp/src/dsp/dec_mips32.c",
-    "../externals/libwebp/src/dsp/dec_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/dec_neon.c",
-    "../externals/libwebp/src/dsp/dec_sse2.c",
-    "../externals/libwebp/src/dsp/dec_sse41.c",
-    "../externals/libwebp/src/dsp/enc.c",
-    "../externals/libwebp/src/dsp/enc_avx2.c",
-    "../externals/libwebp/src/dsp/enc_mips32.c",
-    "../externals/libwebp/src/dsp/enc_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/enc_neon.c",
-    "../externals/libwebp/src/dsp/enc_sse2.c",
-    "../externals/libwebp/src/dsp/enc_sse41.c",
-    "../externals/libwebp/src/dsp/filters.c",
-    "../externals/libwebp/src/dsp/filters_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/filters_sse2.c",
-    "../externals/libwebp/src/dsp/lossless.c",
-    "../externals/libwebp/src/dsp/lossless_enc.c",
-    "../externals/libwebp/src/dsp/lossless_enc_mips32.c",
-    "../externals/libwebp/src/dsp/lossless_enc_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/lossless_enc_neon.c",
-    "../externals/libwebp/src/dsp/lossless_enc_sse2.c",
-    "../externals/libwebp/src/dsp/lossless_enc_sse41.c",
-    "../externals/libwebp/src/dsp/lossless_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/lossless_neon.c",
-    "../externals/libwebp/src/dsp/lossless_sse2.c",
-    "../externals/libwebp/src/dsp/rescaler.c",
-    "../externals/libwebp/src/dsp/rescaler_mips32.c",
-    "../externals/libwebp/src/dsp/rescaler_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/rescaler_neon.c",
-    "../externals/libwebp/src/dsp/rescaler_sse2.c",
-    "../externals/libwebp/src/dsp/upsampling.c",
-    "../externals/libwebp/src/dsp/upsampling_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/upsampling_neon.c",
-    "../externals/libwebp/src/dsp/upsampling_sse2.c",
-    "../externals/libwebp/src/dsp/yuv.c",
-    "../externals/libwebp/src/dsp/yuv_mips32.c",
-    "../externals/libwebp/src/dsp/yuv_mips_dsp_r2.c",
-    "../externals/libwebp/src/dsp/yuv_sse2.c",
-    "../externals/libwebp/src/enc/alpha.c",
-    "../externals/libwebp/src/enc/analysis.c",
-    "../externals/libwebp/src/enc/backward_references.c",
-    "../externals/libwebp/src/enc/config.c",
-    "../externals/libwebp/src/enc/cost.c",
-    "../externals/libwebp/src/enc/filter.c",
-    "../externals/libwebp/src/enc/frame.c",
-    "../externals/libwebp/src/enc/histogram.c",
-    "../externals/libwebp/src/enc/iterator.c",
-    "../externals/libwebp/src/enc/near_lossless.c",
-    "../externals/libwebp/src/enc/picture.c",
-    "../externals/libwebp/src/enc/picture_csp.c",
-    "../externals/libwebp/src/enc/picture_psnr.c",
-    "../externals/libwebp/src/enc/picture_rescale.c",
-    "../externals/libwebp/src/enc/picture_tools.c",
-    "../externals/libwebp/src/enc/quant.c",
-    "../externals/libwebp/src/enc/syntax.c",
-    "../externals/libwebp/src/enc/token.c",
-    "../externals/libwebp/src/enc/tree.c",
-    "../externals/libwebp/src/enc/vp8l.c",
-    "../externals/libwebp/src/enc/webpenc.c",
-    "../externals/libwebp/src/utils/bit_reader.c",
-    "../externals/libwebp/src/utils/bit_writer.c",
-    "../externals/libwebp/src/utils/color_cache.c",
-    "../externals/libwebp/src/utils/filters.c",
-    "../externals/libwebp/src/utils/huffman.c",
-    "../externals/libwebp/src/utils/huffman_encode.c",
-    "../externals/libwebp/src/utils/quant_levels.c",
-    "../externals/libwebp/src/utils/quant_levels_dec.c",
-    "../externals/libwebp/src/utils/random.c",
-    "../externals/libwebp/src/utils/rescaler.c",
-    "../externals/libwebp/src/utils/thread.c",
-    "../externals/libwebp/src/utils/utils.c",
-  ]
+    sources = [
+      "../externals/libwebp/src/dec/alpha.c",
+      "../externals/libwebp/src/dec/buffer.c",
+      "../externals/libwebp/src/dec/frame.c",
+      "../externals/libwebp/src/dec/idec.c",
+      "../externals/libwebp/src/dec/io.c",
+      "../externals/libwebp/src/dec/quant.c",
+      "../externals/libwebp/src/dec/tree.c",
+      "../externals/libwebp/src/dec/vp8.c",
+      "../externals/libwebp/src/dec/vp8l.c",
+      "../externals/libwebp/src/dec/webp.c",
+      "../externals/libwebp/src/demux/demux.c",
+      "../externals/libwebp/src/dsp/alpha_processing.c",
+      "../externals/libwebp/src/dsp/alpha_processing_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/alpha_processing_sse2.c",
+      "../externals/libwebp/src/dsp/alpha_processing_sse41.c",
+      "../externals/libwebp/src/dsp/argb.c",
+      "../externals/libwebp/src/dsp/argb_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/argb_sse2.c",
+      "../externals/libwebp/src/dsp/cost.c",
+      "../externals/libwebp/src/dsp/cost_mips32.c",
+      "../externals/libwebp/src/dsp/cost_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/cost_sse2.c",
+      "../externals/libwebp/src/dsp/cpu.c",
+      "../externals/libwebp/src/dsp/dec.c",
+      "../externals/libwebp/src/dsp/dec_clip_tables.c",
+      "../externals/libwebp/src/dsp/dec_mips32.c",
+      "../externals/libwebp/src/dsp/dec_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/dec_neon.c",
+      "../externals/libwebp/src/dsp/dec_sse2.c",
+      "../externals/libwebp/src/dsp/dec_sse41.c",
+      "../externals/libwebp/src/dsp/enc.c",
+      "../externals/libwebp/src/dsp/enc_avx2.c",
+      "../externals/libwebp/src/dsp/enc_mips32.c",
+      "../externals/libwebp/src/dsp/enc_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/enc_neon.c",
+      "../externals/libwebp/src/dsp/enc_sse2.c",
+      "../externals/libwebp/src/dsp/enc_sse41.c",
+      "../externals/libwebp/src/dsp/filters.c",
+      "../externals/libwebp/src/dsp/filters_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/filters_sse2.c",
+      "../externals/libwebp/src/dsp/lossless.c",
+      "../externals/libwebp/src/dsp/lossless_enc.c",
+      "../externals/libwebp/src/dsp/lossless_enc_mips32.c",
+      "../externals/libwebp/src/dsp/lossless_enc_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/lossless_enc_neon.c",
+      "../externals/libwebp/src/dsp/lossless_enc_sse2.c",
+      "../externals/libwebp/src/dsp/lossless_enc_sse41.c",
+      "../externals/libwebp/src/dsp/lossless_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/lossless_neon.c",
+      "../externals/libwebp/src/dsp/lossless_sse2.c",
+      "../externals/libwebp/src/dsp/rescaler.c",
+      "../externals/libwebp/src/dsp/rescaler_mips32.c",
+      "../externals/libwebp/src/dsp/rescaler_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/rescaler_neon.c",
+      "../externals/libwebp/src/dsp/rescaler_sse2.c",
+      "../externals/libwebp/src/dsp/upsampling.c",
+      "../externals/libwebp/src/dsp/upsampling_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/upsampling_neon.c",
+      "../externals/libwebp/src/dsp/upsampling_sse2.c",
+      "../externals/libwebp/src/dsp/yuv.c",
+      "../externals/libwebp/src/dsp/yuv_mips32.c",
+      "../externals/libwebp/src/dsp/yuv_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/yuv_sse2.c",
+      "../externals/libwebp/src/enc/alpha.c",
+      "../externals/libwebp/src/enc/analysis.c",
+      "../externals/libwebp/src/enc/backward_references.c",
+      "../externals/libwebp/src/enc/config.c",
+      "../externals/libwebp/src/enc/cost.c",
+      "../externals/libwebp/src/enc/filter.c",
+      "../externals/libwebp/src/enc/frame.c",
+      "../externals/libwebp/src/enc/histogram.c",
+      "../externals/libwebp/src/enc/iterator.c",
+      "../externals/libwebp/src/enc/near_lossless.c",
+      "../externals/libwebp/src/enc/picture.c",
+      "../externals/libwebp/src/enc/picture_csp.c",
+      "../externals/libwebp/src/enc/picture_psnr.c",
+      "../externals/libwebp/src/enc/picture_rescale.c",
+      "../externals/libwebp/src/enc/picture_tools.c",
+      "../externals/libwebp/src/enc/quant.c",
+      "../externals/libwebp/src/enc/syntax.c",
+      "../externals/libwebp/src/enc/token.c",
+      "../externals/libwebp/src/enc/tree.c",
+      "../externals/libwebp/src/enc/vp8l.c",
+      "../externals/libwebp/src/enc/webpenc.c",
+      "../externals/libwebp/src/utils/bit_reader.c",
+      "../externals/libwebp/src/utils/bit_writer.c",
+      "../externals/libwebp/src/utils/color_cache.c",
+      "../externals/libwebp/src/utils/filters.c",
+      "../externals/libwebp/src/utils/huffman.c",
+      "../externals/libwebp/src/utils/huffman_encode.c",
+      "../externals/libwebp/src/utils/quant_levels.c",
+      "../externals/libwebp/src/utils/quant_levels_dec.c",
+      "../externals/libwebp/src/utils/random.c",
+      "../externals/libwebp/src/utils/rescaler.c",
+      "../externals/libwebp/src/utils/thread.c",
+      "../externals/libwebp/src/utils/utils.c",
+    ]
+  }
 }