Close ExtensionPopup on tab switches; add test.

chrome/browser/ui/views/extensions/extension_popup.cc

Index: chrome/browser/ui/views/extensions/extension_popup.cc
diff --git a/chrome/browser/ui/views/extensions/extension_popup.cc b/chrome/browser/ui/views/extensions/extension_popup.cc
index 4920c42ee170abd9a4a72f74da47a8bee5b21041..c063bdf7fff496a3890dedc73cfbd0e5c93bea33 100644
--- a/chrome/browser/ui/views/extensions/extension_popup.cc
+++ b/chrome/browser/ui/views/extensions/extension_popup.cc
@@ -15,6 +15,7 @@
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/host_desktop.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "content/public/browser/devtools_agent_host.h"
 #include "content/public/browser/devtools_manager.h"
@@ -94,11 +95,19 @@ ExtensionPopup::ExtensionPopup(extensions::ExtensionViewHost* host,
                  content::Source<BrowserContext>(host->browser_context()));
   content::DevToolsManager::GetInstance()->AddAgentStateCallback(
       devtools_callback_);
+
+  Browser* browser = host_->view()->browser();
+  if (browser && browser->tab_strip_model())

[sky, 2013/12/20 00:14:51]

Can browser really be NULL here? browser->tab_strip_model should never to NULL.

[msw, 2013/12/20 00:46:28]

Done, I removed both checks. I tracked down that the ExtensionViewViews |host|
should never be constructed with a NULL |browser_| for extension popups, which
are VIEW_TYPE_EXTENSION_POPUP, as per extensions::CreateViewHostForExtension:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ext...
That's the only instantiation site, and its |browser_| member is never modified.
+CC jamescook for any additional comments or concerns. 

+    browser->tab_strip_model()->AddObserver(this);
 }
 
 ExtensionPopup::~ExtensionPopup() {
   content::DevToolsManager::GetInstance()->RemoveAgentStateCallback(
       devtools_callback_);
+
+  Browser* browser = host_->view()->browser();
+  if (browser && browser->tab_strip_model())
+    browser->tab_strip_model()->RemoveObserver(this);
 }
 
 void ExtensionPopup::Observe(int type,
@@ -192,6 +201,13 @@ void ExtensionPopup::OnWindowActivated(aura::Window* gained_active,
 }
 #endif
 
+void ExtensionPopup::ActiveTabChanged(content::WebContents* old_contents,
+                                      content::WebContents* new_contents,
+                                      int index,
+                                      int reason) {
+  GetWidget()->Close();
+}
+
 // static
 ExtensionPopup* ExtensionPopup::ShowPopup(const GURL& url,
                                           Browser* browser,