Add sanbdoxed_pages to allow extension/app pages to be served in a sandboxed, unique origin

chrome/common/extensions/extension_manifest_constants.cc

Index: chrome/common/extensions/extension_manifest_constants.cc
diff --git a/chrome/common/extensions/extension_manifest_constants.cc b/chrome/common/extensions/extension_manifest_constants.cc
index e19c30d7d1b29ac35c8d33365cb0cfd85d3b3f81..2fda6da66dc3065b87834824580536ded234c597 100644
--- a/chrome/common/extensions/extension_manifest_constants.cc
+++ b/chrome/common/extensions/extension_manifest_constants.cc
@@ -92,6 +92,8 @@ const char kPluginsPublic[] = "public";
 const char kPublicKey[] = "key";
 const char kRequirements[] = "requirements";
 const char kRunAt[] = "run_at";
+const char kSandboxedPages[] = "sandboxed_pages.pages";
+const char kSandboxedPagesCSP[] = "sandboxed_pages.content_security_policy";
 const char kShiftKey[] = "shiftKey";
 const char kShortcutKey[] = "shortcutKey";
 const char kSignature[] = "signature";
@@ -391,6 +393,12 @@ const char kInvalidRequirements[] =
     "Invalid value for 'requirements'";
 const char kInvalidRunAt[] =
     "Invalid value for 'content_scripts[*].run_at'.";
+const char kInvalidSandboxedPagesList[] =
+    "Invalid value for 'sandboxed_pages.pages'.";
+const char kInvalidSandboxedPage[] =
+    "Invalid value for 'sandboxed_pages.pages[*]'.";
+const char kInvalidSandboxedPagesCSP[] =
+    "Invalid value for 'sandboxed_pages.content_security_policy'.";
 const char kInvalidSignature[] =
     "Value 'signature' is missing or invalid.";
 const char kInvalidTheme[] =