Add experimental code behind a flag for Content Size Policy

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index f2d8e9a90b830d39f5267c0c6e80a4eb8ecf1ce6..fcd508d561e7514355b679e60ed09ee5fe56051f 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -873,6 +873,9 @@ const char kEnableNativeGpuMemoryBuffers[] = "enable-native-gpu-memory-buffers";
 // Texture target for CHROMIUM_image backed content textures.
 const char kContentImageTextureTarget[] = "content-image-texture-target";
 
+// The max total content size a cross-site subframe can use. In bytes.
+const char kContentSizePolicy[] = "content-size-policy";
+
 // Texture target for CHROMIUM_image backed video frame textures.
 const char kVideoImageTextureTarget[] = "video-image-texture-target";