Removing GetSiteForURL() call from ExtensionWebContentsObserver.

Replacing site URL comparison with a check that compares extension
pointers. This is similar to ProcessManager::GetExtensionForWebContents()
code which appears to be trying to accomplish the same goal. This change
is part of an effort to remove site URL usage across the code base.

Bug: 1085275
Change-Id: Ice16e145849786eabcfbe5fd05861528a2beb8a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2212785
Commit-Queue: Aaron Colwell <acolwell@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Auto-Submit: Aaron Colwell <acolwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818027}

extensions/browser/extension_web_contents_observer.cc

@@ -292,12 +292,14 @@ const Extension* ExtensionWebContentsObserver::GetExtensionFromFrame(
 
   if (verify_url) {
     const url::Origin& origin(render_frame_host->GetLastCommittedOrigin());
-    // Without site isolation, this check is needed to eliminate non-extension
-    // schemes. With site isolation, this is still needed to exclude sandboxed
-    // extension frames with an opaque origin.
-    const GURL site_url(render_frame_host->GetSiteInstance()->GetSiteURL());
-    if (origin.opaque() || site_url != content::SiteInstance::GetSiteForURL(
-                                           browser_context, origin.GetURL()))
+    // This check is needed to eliminate origins that are not within a
+    // hosted-app's web extent, and sandboxed extension frames with an opaque
+    // origin.
+    // TODO(1139108) See if extension check is still needed after bug is fixed.
+    auto* extension_for_origin = ExtensionRegistry::Get(browser_context)
+                                     ->enabled_extensions()
+                                     .GetExtensionOrAppByURL(origin.GetURL());
+    if (origin.opaque() || extension_for_origin != extension)
       return nullptr;
   }