Implements PrintBrowser mode.

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5

 {
   // http://dev.chromium.org/blink/runtime-enabled-features
   //
   // This list is used to generate RuntimeEnabledFeatures.h/cpp which contains
   // a class that stores static enablers for all experimental features.
 
   parameters: {
     // Each feature can be assigned a "status":
     // status=stable -> Enable this in all Blink configurations.  We are committed to these APIs indefinitely.
     // status=experimental -> In-progress features, Web Developers might play with, but are not on by default in stable.
@@ skipping 683 matching lines @@
       status: "experimental",
     },
     {
       name: "PointerEvent",
       status: "stable",
     },
     {
       name: "PreciseMemoryInfo",
     },
     {
+      name: "PrintBrowser",
+    },
+    {
       name: "PreferredImageRasterBounds",
       settable_from_internals: true,
     },
     // This feature is deprecated and we are evangelizing affected sites.
     // See https://crbug.com/346236 for current status.
     {
       name: "PrefixedVideoFullscreen",
       status: "stable",
     },
     {
@@ skipping 84 matching lines @@
       name: "SharedWorker",
       status: "stable",
     },
     {
       name: "SlimmingPaintInvalidation",
       implied_by: ["SlimmingPaintV2"],
       status: "stable",
     },
     {
       name: "SlimmingPaintV2",
+      implied_by: ["PrintBrowser"],
     },
     {
       name: "SlimmingPaintStrictCullRectClipping",
     },
     // Used as argument in attribute of stable-release functions/interfaces where
     // a runtime-enabled feature name is required for correct IDL syntax.
     // This is a global flag; do not change its status.
     {
       name: "StableBlinkFeatures",
       status: "stable",
@@ skipping 183 matching lines @@
     {
       name: "UnclosedFormControlIsInvalid",
       status: "experimental",
     },
     {
       name: "RestrictCompleteURLCharacterSet",
       status: "experimental",
     },
   ],
 }