NOT YET READY: Improve granularity of window namespaces in Blink.

extensions/renderer/extension_frame_helper.cc

Index: extensions/renderer/extension_frame_helper.cc
diff --git a/extensions/renderer/extension_frame_helper.cc b/extensions/renderer/extension_frame_helper.cc
index da47e687f5662c0d8eefb6830a860edf971c2689..6a91e015b28e65a673f9ba84220d35c67f76394c 100644
--- a/extensions/renderer/extension_frame_helper.cc
+++ b/extensions/renderer/extension_frame_helper.cc
@@ -17,6 +17,7 @@
 #include "extensions/renderer/content_watcher.h"
 #include "extensions/renderer/dispatcher.h"
 #include "extensions/renderer/messaging_bindings.h"
+#include "extensions/renderer/renderer_extension_registry.h"
 #include "extensions/renderer/script_context.h"
 #include "third_party/WebKit/public/platform/WebSecurityOrigin.h"
 #include "third_party/WebKit/public/web/WebConsoleMessage.h"
@@ -139,6 +140,34 @@ content::RenderFrame* ExtensionFrameHelper::GetBackgroundPageFrame(
   return nullptr;
 }
 
+// static
+content::RenderFrame* ExtensionFrameHelper::FindFrame(
+    content::RenderFrame* relative_to_frame,
+    const std::string& name) {
+  // Only pierce browsing instance boundaries if |relative_to_frame| is an
+  // extension.
+  GURL effective_url = ScriptContext::GetEffectiveDocumentURL(
+      relative_to_frame->GetWebFrame(),
+      relative_to_frame->GetWebFrame()->GetDocument().Url(), true);
+  const Extension* extension =
+      extensions::RendererExtensionRegistry::Get()->GetExtensionOrAppByURL(
+          effective_url);
+  if (!extension)
+    return nullptr;
+
+  // Try to match all same-origin frames in this process.
+  for (const ExtensionFrameHelper* helper : g_frame_helpers.Get()) {
+    if (!relative_to_frame->GetWebFrame()->GetSecurityOrigin().CanAccess(
+            helper->render_frame()->GetWebFrame()->GetSecurityOrigin()))
+      continue;
+
+    if (helper->render_frame()->GetWebFrame()->AssignedName().Utf8() == name)
+      return helper->render_frame();
+  }
+
+  return nullptr;
+}
+
 // static
 bool ExtensionFrameHelper::IsContextForEventPage(const ScriptContext* context) {
   content::RenderFrame* render_frame = context->GetRenderFrame();