[WIP] Synthetic repro for bug 693720

chrome/common/chrome_content_client.cc

Index: chrome/common/chrome_content_client.cc
diff --git a/chrome/common/chrome_content_client.cc b/chrome/common/chrome_content_client.cc
index 91acb7d5f6cee2592df87450f8da7967c4ada7cd..7cc75b449ce4c2cba9c5f25a9f308b6e8f2c8b35 100644
--- a/chrome/common/chrome_content_client.cc
+++ b/chrome/common/chrome_content_client.cc
@@ -41,6 +41,7 @@
 #include "content/public/common/url_constants.h"
 #include "content/public/common/user_agent.h"
 #include "extensions/common/constants.h"
+#include "extensions/common/switches.h"
 #include "extensions/features/features.h"
 #include "gpu/config/gpu_info.h"
 #include "media/media_features.h"
@@ -619,7 +620,16 @@ void ChromeContentClient::AddAdditionalSchemes(Schemes* schemes) {
   // TODO(kalman): See what happens with a service worker.
   schemes->cors_enabled_schemes.push_back(extensions::kExtensionScheme);
 
-  schemes->csp_bypassing_schemes.push_back(extensions::kExtensionScheme);
+  // Outside of extension processes, Content Security Policy cannot be used to
+  // block the chrome-extension:// scheme. This is to prevent a page from using
+  // CSP to block user scripts. Within app/extension processes, this bypass is
+  // not necessary. And within isolated app processes, we rely on a restrictive
+  // CSP to ensure isolation of the StoragePartition, so it's important that
+  // other extensions be blocked.
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          extensions::switches::kExtensionProcess)) {
+    schemes->csp_bypassing_schemes.push_back(extensions::kExtensionScheme);
+  }
 #endif
 
 #if defined(OS_CHROMEOS)