Move Pepper 3D Image Chromium behind an experiment.

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index 06b7faabd407e320549908af58332bc599fafdc9..31d7aefcd42a438a13aaf29edcb7ea011fb83365 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -99,6 +99,11 @@ const base::Feature kPassiveDocumentEventListeners{
 const base::Feature kPointerEvents{"PointerEvent",
                                    base::FEATURE_DISABLED_BY_DEFAULT};
 
+// If Pepper 3D Image Chromium is allowed, this feature controls whether it is
+// enabled.
+const base::Feature kPepper3DImageChromium{"Pepper3DImageChromium",
+                                           base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Throttle Blink's rendering pipeline based on frame visibility.
 const base::Feature kRenderingPipelineThrottling{
     "RenderingPipelineThrottling", base::FEATURE_ENABLED_BY_DEFAULT};