Roll ahead to fix and update .gni to unbreak shaderc

Roll third_party/spirv-cross/ 5431e1da2..e5d3a6655 (8 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Cross/+log/5431e1da2dc1..e5d3a6655e13

$ git log 5431e1da2..e5d3a6655 --date=short --no-merges --format='%ad %ae %s'
2019-10-07 rharrison Update SPV_VERSION from 1.4 to 1.5
2019-10-07 post Workaround MSVC issue.
2019-10-07 post Do not consider aliased struct types if the master is not a block.
2019-10-07 post Run format_all.sh.
2019-10-04 post Do not value compare JSON files for regression purposes.
2019-10-04 post Reflect: Deal with workgroup size being specialization constants.
2019-10-03 frank.richter reference: Update to include workgroup_size
2019-10-03 frank.richter reflection: Write workgroup_size to JSON for compute shaders

Created with:
  roll-dep third_party/spirv-cross

Roll third_party/shaderc/ e849e6783..621605ce2 (10 commits)

$ git log e849e6783..621605ce2 --date=short --no-merges --format='%ad %ae %s'
2019-10-08 rharrison Fix various build issues for chromium & dawn (#835)
2019-10-08 stevenperron Use a better python idiom (#834)
2019-10-08 stevenperron Fix up use of private spirv-tools headers. (#833)
2019-10-07 rharrison Roll spirv-cross ahead and update known_failures to fix build breakage (#831)
2019-10-07 9856269+sarahM0 spvc: Add an empty opt pass (#816)
2019-10-07 9856269+sarahM0 spvc: Add known_invalid file (#823)
2019-10-04 dneto Add support for targeting SPIR-V 1.5 (#822)
2019-10-03 rharrison Revert "Add spvc compiler to returned result (#821)" (#827)
2019-10-03 rharrison Add spvc compiler to returned result (#821)
2019-10-02 rharrison Rolling 4 dependencies (#817)

Created with:
  roll-dep third_party/shaderc

Change-Id: I9e77d5c78eb647c1f117c356306e6dff7613722a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/11963
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/DEPS b/DEPS
index 3101688..2d76319 100644
--- a/DEPS
+++ b/DEPS
@@ -50,7 +50,7 @@
 
   # SPIRV-Cross
   'third_party/spirv-cross': {
-    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Cross@5431e1da2dc11123750f39a5ba4e5a8c117a0773',
+    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Cross@e5d3a6655e13870a6f38f40bd88cc662b14e3cdf',
     'condition': 'dawn_standalone',
   },
 
@@ -68,7 +68,7 @@
     'condition': 'dawn_standalone',
   },
   'third_party/shaderc': {
-    'url': '{chromium_git}/external/github.com/google/shaderc@e849e6783d9f99fd7727d12f0cf2321269beca17',
+    'url': '{chromium_git}/external/github.com/google/shaderc@621605ce2644d55ab74cb27a8afef97dc40f1b0f',
     'condition': 'dawn_standalone',
   },
 
diff --git a/build_overrides/shaderc.gni b/build_overrides/shaderc.gni
index 1cb6bd1..64a743a 100644
--- a/build_overrides/shaderc.gni
+++ b/build_overrides/shaderc.gni
@@ -15,3 +15,6 @@
 shaderc_glslang_dir = "//third_party/glslang"
 shaderc_spirv_tools_dir = "//third_party/SPIRV-Tools"
 shaderc_spirv_cross_dir = "//third_party"
+shaderc_spirv_headers_dir = "//third_party/spirv-headers"
+
+shaderc_enable_spvc_parser = false