From f332895773f5016da5bf0c8ddda6fcdcdf0b4603 Mon Sep 17 00:00:00 2001
From: Holden Warriner <hwarriner@google.com>
Date: Fri, 7 Feb 2025 16:29:22 -0500
Subject: [PATCH] Add CobaltRenderFrameObserver comments, style fix

b/393406740
---
 cobalt/renderer/cobalt_render_frame_observer.cc | 6 +++++-
 cobalt/renderer/cobalt_render_frame_observer.h  | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/cobalt/renderer/cobalt_render_frame_observer.cc b/cobalt/renderer/cobalt_render_frame_observer.cc
index f46c9764ee4..7bec95f4482 100644
--- a/cobalt/renderer/cobalt_render_frame_observer.cc
+++ b/cobalt/renderer/cobalt_render_frame_observer.cc
@@ -32,8 +32,12 @@ void CobaltRenderFrameObserver::OnDestruct() {
 }
 
 void CobaltRenderFrameObserver::DidClearWindowObject() {
-  auto& cmd = *base::CommandLine::ForCurrentProcess();
+  const auto& cmd = *base::CommandLine::ForCurrentProcess();
   if (cmd.HasSwitch(switches::kExposeInternalsForTesting)) {
+    // The internals object is injected here so that window.internals is exposed
+    // to JavaScript at initial load of the web app, when the frame navigates
+    // from the initial empty document to the actual document. This approach is
+    // borrowed from content shell.
     blink::WebTestingSupport::InjectInternalsObject(
         render_frame()->GetWebFrame());
   }
diff --git a/cobalt/renderer/cobalt_render_frame_observer.h b/cobalt/renderer/cobalt_render_frame_observer.h
index 6f6161840b0..f84081e6b08 100644
--- a/cobalt/renderer/cobalt_render_frame_observer.h
+++ b/cobalt/renderer/cobalt_render_frame_observer.h
@@ -20,6 +20,7 @@
 
 namespace cobalt {
 
+// Enables Cobalt-specific responses to notifications of changes to the frame.
 class CobaltRenderFrameObserver : public content::RenderFrameObserver {
  public:
   explicit CobaltRenderFrameObserver(content::RenderFrame* render_frame);
@@ -30,7 +31,14 @@ class CobaltRenderFrameObserver : public content::RenderFrameObserver {
       delete;
 
  private:
+  // content::RenderFrameObserver impl.
+
+  // Overridden so that the observer has the same lifetime as the RenderFrame.
   void OnDestruct() override;
+
+  // Overridden for Cobalt-specific responses to this particular notification.
+  // See blink::WebLocalFrameClient.DidClearWindowObject() for details about
+  // when it's sent.
   void DidClearWindowObject() override;
 };