Only observe the original active web contents when view is created.

Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Bug: b:273785262
Change-Id: I301b24817faaef9b5b5f12e2e4beadeb26824a9a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4350424
Commit-Queue: Juan Mojica <juanmojica@google.com>
Commit-Queue: Ali Stanfield <stanfield@google.com>
Reviewed-by: Ali Stanfield <stanfield@google.com>
Auto-Submit: Juan Mojica <juanmojica@google.com>
Cr-Commit-Position: refs/heads/main@{#1118941}

chrome/browser/ui/webui/side_panel/companion/companion_page_handler.cc

@@ -17,33 +17,16 @@ CompanionPageHandler::CompanionPageHandler(
     mojo::PendingRemote<side_panel::mojom::CompanionPage> page,
     Browser* browser,
     CompanionSidePanelUntrustedUI* companion_untrusted_ui)
-    : receiver_(this, std::move(receiver)),
+    : content::WebContentsObserver(
+          browser->tab_strip_model()->GetActiveWebContents()),
+      receiver_(this, std::move(receiver)),
       page_(std::move(page)),
-      browser_(browser),
       companion_untrusted_ui_(companion_untrusted_ui) {
-  DCHECK(browser_);
-  browser_->tab_strip_model()->AddObserver(this);
-
-  // Observe the active web contents and then pass the current active visible
-  // URL to the WebUI.
-  Observe(browser_->tab_strip_model()->GetActiveWebContents());
+  DCHECK(browser);
   NotifyURLChanged();
 }
 
-CompanionPageHandler::~CompanionPageHandler() {
-  browser_->tab_strip_model()->RemoveObserver(this);
-  Observe(nullptr);
-}
-
-void CompanionPageHandler::OnTabStripModelChanged(
-    TabStripModel* tab_strip_model,
-    const TabStripModelChange& change,
-    const TabStripSelectionChange& selection) {
-  if (selection.active_tab_changed() && selection.new_contents) {
-    Observe(selection.new_contents);
-    NotifyURLChanged();
-  }
-}
+CompanionPageHandler::~CompanionPageHandler() = default;
 
 void CompanionPageHandler::PrimaryPageChanged(content::Page& page) {
   NotifyURLChanged();

chrome/browser/ui/webui/side_panel/companion/companion_page_handler.h

@@ -6,7 +6,6 @@
 #define CHROME_BROWSER_UI_WEBUI_SIDE_PANEL_COMPANION_COMPANION_PAGE_HANDLER_H_
 
 #include "base/memory/raw_ptr.h"
-#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
 #include "chrome/browser/ui/webui/side_panel/companion/companion.mojom.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "mojo/public/cpp/bindings/pending_receiver.h"
@@ -27,7 +26,6 @@ inline constexpr char kOriginQueryParameterValue[] =
     "chrome-untrusted://companion-side-panel.top-chrome";
 
 class CompanionPageHandler : public side_panel::mojom::CompanionPageHandler,
-                             public TabStripModelObserver,
                              public content::WebContentsObserver {
  public:
   explicit CompanionPageHandler(
@@ -42,12 +40,6 @@ class CompanionPageHandler : public side_panel::mojom::CompanionPageHandler,
   // side_panel::mojom::CompanionPageHandler:
   void ShowUI() override;
 
-  // TabStripModelObserver:
-  void OnTabStripModelChanged(
-      TabStripModel* tab_strip_model,
-      const TabStripModelChange& change,
-      const TabStripSelectionChange& selection) override;
-
   // content::WebContentsObserver:
   void PrimaryPageChanged(content::Page& page) override;
 
@@ -64,7 +56,6 @@ class CompanionPageHandler : public side_panel::mojom::CompanionPageHandler,
 
   mojo::Receiver<side_panel::mojom::CompanionPageHandler> receiver_;
   mojo::Remote<side_panel::mojom::CompanionPage> page_;
-  const raw_ptr<Browser> browser_;
   raw_ptr<CompanionSidePanelUntrustedUI> companion_untrusted_ui_ = nullptr;
 };