Enable the passthrough command decoder by default on Windows.

The finch release process says that the feature should be enabled in
Chrome ToT at the same time as it is launched so that a max_version can
be set.

BUG=882580

Change-Id: I4b3e3eb70236dab1f4269ef9f38073c89a93d8b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1736798Reviewed-by: Jonathan Backer <backer@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#684382}

ui/gl/gl_features.cc

@@ -10,7 +10,14 @@ namespace features {
 // the --use-cmd-decoder=passthrough or --use-cmd-decoder=validating flags.
 // Feature lives in ui/gl because it affects the GL binding initialization on
 // platforms that would otherwise not default to using EGL bindings.
+// Launched on Windows, still experimental on other platforms.
 const base::Feature kDefaultPassthroughCommandDecoder{
-    "DefaultPassthroughCommandDecoder", base::FEATURE_DISABLED_BY_DEFAULT};
+  "DefaultPassthroughCommandDecoder",
+#if defined(OS_WIN)
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif
+};
 
-}  // namespace features
\ No newline at end of file
+}  // namespace features