Fix for WebView accessible resources.

extensions/browser/renderer_startup_helper.cc

Index: extensions/browser/renderer_startup_helper.cc
diff --git a/extensions/browser/renderer_startup_helper.cc b/extensions/browser/renderer_startup_helper.cc
index 51dcbdd3a0d48cf0267e18ad8ee82a323dc99c20..917a35ba49fefa2a80ffa1d6a90333b1525c8505 100644
--- a/extensions/browser/renderer_startup_helper.cc
+++ b/extensions/browser/renderer_startup_helper.cc
@@ -12,6 +12,7 @@
 #include "extensions/browser/extension_function_dispatcher.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extensions_browser_client.h"
+#include "extensions/browser/guest_view/web_view/web_view_guest.h"
 #include "extensions/common/extension_messages.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/extensions_client.h"
@@ -51,6 +52,14 @@ void RendererStartupHelper::Observe(
   process->Send(new ExtensionMsg_SetScriptingWhitelist(
       extensions::ExtensionsClient::Get()->GetScriptingWhitelist()));
 
+  // If the new render process is a WebView guest process, propagate the WebView
+  // partition ID to it.
+  std::string webview_partition_id = WebViewGuest::GetPartitionID(process);
+  if (!webview_partition_id.empty()) {
+    process->Send(new ExtensionMsg_SetWebViewPartitionID(
+        WebViewGuest::GetPartitionID(process)));
+  }
+
   // Loaded extensions.
   std::vector<ExtensionMsg_Loaded_Params> loaded_extensions;
   const ExtensionSet& extensions =