Hook the PerformanceManagerTabHelper to ChromeWebDialogView's WebView

The PerformanceManagerTabHelper reflects WebContents and their frame
trees into the PerformanceManager graph. This CL gives the graph
visibility for the WebContents created by ChromeWebDialogView.

Bug: 1046881
Change-Id: I0b60996a1883a3be5f85f505576e1618ad347061
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036479Reviewed-by: Collin Baker <collinbaker@chromium.org>
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738000}

chrome/browser/ui/views/chrome_web_dialog_view.cc

@@ -9,6 +9,7 @@
 #include "build/build_config.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/ui/webui/chrome_web_contents_handler.h"
+#include "components/performance_manager/embedder/performance_manager_registry.h"
 #include "ui/views/controls/webview/web_dialog_view.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/window/dialog_delegate.h"
@@ -38,6 +39,9 @@ gfx::NativeWindow CreateWebDialogWidget(views::Widget::InitParams params,
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       view->web_contents());
 
+  performance_manager::PerformanceManagerRegistry::GetInstance()
+      ->CreatePageNodeForWebContents(view->web_contents());
+
   if (show)
     widget->Show();
   return widget->GetNativeWindow();