Roll ahead to fix and update .gni to unbreak shaderc

Roll src/third_party/spirv-cross/spirv-cross/ ffca8735f..e5d3a6655 (48 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Cross.git/+log/ffca8735ff42..e5d3a6655e13

$ git log ffca8735f..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
2019-09-19 post Update SPIR-V headers.
2019-09-19 post MSL: Fix 16-bit integer literals.
2019-09-18 rharrison Update external/ to SPIR-V 1.5
2019-09-18 post CMake: Add option to force -fPIC.
2019-09-17 post Fix -Wshorten-64-to-32 warnings.
2019-09-16 post CMake: Add option to skip installation targets.
2019-09-12 post Consider discard and demote as impure statements.
2019-09-06 wadetb MSL: Fix array copies to/from interpolators
2019-09-06 post Run format_all.sh.
2019-09-05 post Refactor into stronger types in public API.
2019-09-06 post Add dynamic offsets to C API.
2019-09-06 post Fix some issues on certain compilers.
2019-09-05 cdavis MSL: Support dynamic offsets for buffers in argument buffers.
2019-09-04 cdavis MSL: Force storage images on iOS to use discrete descriptors.
2019-09-05 lifeng.pan Fix ParsedIR::mark_used_as_array_length(uint32_t id)
2019-09-04 post Add test case for interlocks in control flow.
2019-09-04 post Make sure not to propagate loads outside interlock region.
2019-09-04 post Add interlock test for split functions doing begin/end.
2019-09-04 post Deal with complex interlock cases in GLSL.
2019-09-04 post Add test shader for simple case of interlocked callstack.
2019-09-04 post Deal with call stacks when analyzing access.
2019-09-04 post Analyze complex cases for fragment interlocks.
2019-08-04 cdavis Support the SPV_EXT_fragment_shader_interlock extension.
2019-08-02 cdavis MSL: Add support for sampler Y'CbCr conversion.
2019-08-30 t.roughton Clang-format changes
2019-08-30 t.roughton Update tests to account for all non-entry-point functions being inlined
2019-08-29 post MSL: Add {Base,}{Vertex,Instance}Index to bitcast_from_builtin_load.
2019-08-29 t.roughton Inline all non-entry-point functions
2019-06-10 t.roughton MSL: inline all emitted functions
2019-08-02 cdavis GLSL: Fix post-depth coverage for ESSL.
2019-08-28 post Run format_all.sh.
2019-08-27 post GLSL: Assume image and sampler can be RelaxedPrecision.
2019-08-27 post MSL: Deal with array copies from and to threadgroup.
2019-08-27 post Do not allow base expressions for non-native row-major matrices.
2019-08-27 post Deal with ldexp taking uint input.
2019-08-26 post Move branchless analysis to CFG.
2019-08-26 post Elide branches to continue block when continue block is also a merge.
2019-08-26 post Deal correctly with sign on bitfield operations.
2019-08-26 post Fix variable scope when switch block exits multiple times.
2019-08-01 post Fix severe performance issue with invariant expression invalidation.

Created with:
  roll-dep src/third_party/spirv-cross/spirv-cross

Roll src/third_party/shaderc/src/ 614d79248..621605ce2 (7 commits)

https://chromium.googlesource.com/external/github.com/google/shaderc.git/+log/614d79248ef2..621605ce2644

$ git log 614d79248..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)

Created with:
  roll-dep src/third_party/shaderc/src

Change-Id: If0cdecfa6b873dcc66fe81867021566dfaaba18b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1848358
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704174}

DEPS

@@ -294,11 +294,11 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'spirv_cross_revision': 'ffca8735ff42a9e7a3d1dbb984cf3bf2ca724ebc',
+  'spirv_cross_revision': 'e5d3a6655e13870a6f38f40bd88cc662b14e3cdf',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'shaderc_revision': '614d79248ef2dea617085475f8d64148b37d7296',
+  'shaderc_revision': '621605ce2644d55ab74cb27a8afef97dc40f1b0f',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.

build_overrides/shaderc.gni

@@ -5,3 +5,6 @@
 shaderc_glslang_dir = "//third_party/glslang/src"
 shaderc_spirv_tools_dir = "//third_party/SPIRV-Tools/src"
 shaderc_spirv_cross_dir = "//third_party/dawn/third_party"
+shaderc_spirv_headers_dir = "//third_party/spirv-headers/src"
+
+shaderc_enable_spvc_parser = false