Revert "Re-land sksl fragment processor support"

This reverts commit c070939fd1a954b7a492bc30f0cf64a664b90181.

Reason for revert: 

This has some knock-on effects in the generation of Android.bp from our GN files.  See gn/gn_to_bp.py?  We're seeing things like "tmp/tmpsBVycx/gen/" end up in the include search path in Android.bp, which obviously don't exist there...

Original change's description:
> Re-land sksl fragment processor support
> 
> This reverts commit ed50200682e0de72c3abecaa4d5324ebcd1ed9f9.
> 
> Bug: skia:
> Change-Id: I9caa7454b391450620d6989dc472abb3cf7a2cab
> Reviewed-on: https://skia-review.googlesource.com/20965
> Reviewed-by: Ben Wagner <benjaminwagner@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

TBR=benjaminwagner@google.com,ethannicholas@google.com

Change-Id: I502486b5405923b322429219f4cc396a45a14cea
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/20990
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 7595076..9ba71b2 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -139,7 +139,6 @@
     "src/utils/win",
     "src/xml",
     "third_party/gif",
-    "$target_gen_dir",
   ]
 
   defines = [ "SK_GAMMA_APPLY_TO_A8" ]
@@ -346,9 +345,6 @@
 
 optional("effects") {
   enabled = skia_enable_effects
-  deps = [
-    ":compile_processors",
-  ]
   sources =
       skia_effects_sources + [ "src/ports/SkGlobalInitialization_default.cpp" ]
   sources_when_disabled = [ "src/ports/SkGlobalInitialization_none.cpp" ]
@@ -414,68 +410,12 @@
   ]
 }
 
-if (skia_enable_gpu && skia_gpu_processor_sources != []) {
-  executable("skslc") {
-    defines = [ "SKSL_STANDALONE" ]
-    sources = [
-      "src/sksl/SkSLMain.cpp",
-    ]
-    sources += skia_sksl_sources
-    include_dirs = [
-      "src/gpu",
-      "src/sksl",
-    ]
-    deps = [
-      "//third_party/spirv-tools",
-    ]
-  }
-
-  skia_gpu_processor_outputs = []
-  foreach(src, skia_gpu_processor_sources) {
-    name = get_path_info(src, "name")
-    skia_gpu_processor_outputs += [
-      "$target_gen_dir/effects/$name.h",
-      "$target_gen_dir/effects/$name.cpp",
-    ]
-  }
-
-  action("compile_processors") {
-    script = "gn/compile_processors.py"
-    deps = [
-      ":skslc(//gn/toolchain:$host_toolchain)",
-    ]
-    sources = skia_gpu_processor_sources
-    outputs = skia_gpu_processor_outputs
-    skslc_path = "$root_out_dir/"
-    if (host_toolchain != default_toolchain_name) {
-      skslc_path += "$host_toolchain/"
-    }
-    skslc_path += "skslc"
-    if (host_os == "win") {
-      skslc_path = ".exe"
-    }
-    args = [
-      rebase_path(skslc_path),
-      rebase_path("$target_gen_dir/effects"),
-    ]
-    args += rebase_path(skia_gpu_processor_sources)
-  }
-} else {
-  skia_gpu_processor_outputs = []
-  group("compile_processors") {
-  }
-}
-
 optional("gpu") {
   enabled = skia_enable_gpu
-  deps = [
-    ":compile_processors",
-  ]
   public_defines = []
 
   sources = skia_gpu_sources + skia_sksl_sources +
-            [ "src/gpu/gl/GrGLDefaultInterface_native.cpp" ] +
-            skia_gpu_processor_outputs
+            [ "src/gpu/gl/GrGLDefaultInterface_native.cpp" ]
 
   # These paths need to be absolute to match the ones produced by shared_sources.gni.
   sources -= get_path_info([
@@ -519,7 +459,9 @@
     }
   }
   if (skia_enable_spirv_validation) {
-    deps += [ "//third_party/spirv-tools" ]
+    deps = [
+      "//third_party/spirv-tools",
+    ]
     public_defines += [ "SK_ENABLE_SPIRV_VALIDATION" ]
   }
 }
@@ -1588,4 +1530,15 @@
       ]
     }
   }
+
+  if (skia_enable_gpu) {
+    test_app("skslc") {
+      defines = [ "SKSL_STANDALONE" ]
+      sources = [
+        "src/sksl/SkSLMain.cpp",
+      ]
+      sources += skia_sksl_sources
+      include_dirs = [ "src/sksl" ]
+    }
+  }
 }