Propagate kDisableMetalTestShaders to Gpu process

TBR=kbr

Bug: 1085899
Change-Id: I6df96e0cebcb1b85d4af3674e02ef2936b5a1349
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2227973Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: ccameron <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774522}

content/browser/BUILD.gn

@@ -2114,6 +2114,7 @@ jumbo_source_set("browser") {
       "sandbox_support_mac_impl.mm",
     ]
     deps += [
+      "//components/metal_util",
       "//components/remote_cocoa/app_shim",
       "//components/remote_cocoa/browser",
       "//components/remote_cocoa/common:mojo",

content/browser/gpu/DEPS

 include_rules = [
+  "+components/metal_util",
   "+components/ui_devtools/buildflags.h",
 ]
 

content/browser/gpu/gpu_process_host.cc

@@ -101,6 +101,7 @@
 #endif
 
 #if defined(OS_MACOSX)
+#include "components/metal_util/switches.h"
 #include "content/browser/gpu/ca_transaction_gpu_coordinator.h"
 #endif
 
@@ -255,6 +256,7 @@ static const char* const kSwitchNames[] = {
     service_manager::switches::kEnableSandboxLogging,
     switches::kDisableAVFoundationOverlays,
     switches::kDisableMacOverlays,
+    switches::kDisableMetalTestShaders,
     switches::kDisableRemoteCoreAnimation,
     switches::kShowMacOverlayBorders,
     switches::kUseHighGPUThreadPriorityForPerfTests,