Revert "Enable the passthrough command decoder by default on Windows."

This reverts commit 1140edbf.

Reason for revert: This enables the feature on stable by default and causes GPU memory usage to grow indefinitely because GPU discardable textures aren't implemented in passthrough. See crbug.com/881303

Original change's description:
> Enable the passthrough command decoder by default on Windows.
> 
> This ensures that the passthrough command decoder is tested on developer
> builds.
> 
> BUG=738568
> BUG=602688
> 
> Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
> Change-Id: I3cb473c51d8c889f958827233ca67d6cf6b7fb04
> Reviewed-on: https://chromium-review.googlesource.com/1075507
> Reviewed-by: Antoine Labour <piman@chromium.org>
> Commit-Queue: Geoff Lang <geofflang@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#562533}

TBR=geofflang@chromium.org,piman@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 738568, 602688, 881303
Change-Id: I302775b317de7732753cd48fe9d470a35520679f
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/1213958Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589757}

gpu/config/gpu_finch_features.cc

@@ -26,13 +26,7 @@ const base::Feature kDefaultEnableOopRasterization{
 // Use the passthrough command decoder by default.  This can be overridden with
 // the --use-cmd-decoder=passthrough or --use-cmd-decoder=validating flags.
 const base::Feature kDefaultPassthroughCommandDecoder{
-  "DefaultPassthroughCommandDecoder",
-#if defined(OS_WIN)
-      base::FEATURE_ENABLED_BY_DEFAULT
-#else
-      base::FEATURE_DISABLED_BY_DEFAULT
-#endif
-};
+    "DefaultPassthroughCommandDecoder", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Use DirectComposition layers (overlays) for video if supported. Overridden by
 // --enable-direct-composition-layers and --disable-direct-composition-layers.