Refactor RenderWidgetHost::set_paint_observer()

chrome/browser/instant/instant_loader.cc

Index: chrome/browser/instant/instant_loader.cc
diff --git a/chrome/browser/instant/instant_loader.cc b/chrome/browser/instant/instant_loader.cc
index b6b47a6d1595336eafe5b37c53f5b288353a760e..fdcfe399e365ccd1dcd120318f4106d82eb2c41c 100644
--- a/chrome/browser/instant/instant_loader.cc
+++ b/chrome/browser/instant/instant_loader.cc
@@ -33,6 +33,7 @@
 #include "chrome/common/notification_details.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
+#include "chrome/common/notification_service.h"
 #include "chrome/common/notification_source.h"
 #include "chrome/common/notification_type.h"
 #include "chrome/common/page_transition_types.h"
@@ -133,30 +134,26 @@ class InstantLoader::FrameLoadObserver : public NotificationObserver {
 // tracked by TabContentsDelegateImpl, but owned by RenderWidgetHost. When
 // deleted this notifies the TabContentsDelegateImpl so that it can clean
 // up appropriately.
-class InstantLoader::PaintObserverImpl
-    : public RenderWidgetHost::PaintObserver {
+class InstantLoader::PaintObserverImpl : public NotificationObserver {
  public:
   PaintObserverImpl(TabContentsDelegateImpl* delegate,
-                    RenderWidgetHost* rwh)
-      : delegate_(delegate),
-        rwh_(rwh) {
-    rwh_->set_paint_observer(this);
+                    RenderWidgetHost* render_widget_host)
+      : delegate_(delegate) {
+    registrar_.Add(this, NotificationType::RENDER_WIDGET_HOST_DID_PAINT,
+        Source<RenderWidgetHost>(render_widget_host));
+    registrar_.Add(this, NotificationType::RENDER_WIDGET_HOST_DESTROYED,
+        Source<RenderWidgetHost>(render_widget_host));
   }
 
   ~PaintObserverImpl();
 
-  // Deletes this object by resetting the PaintObserver on the RenderWidgetHost.
-  void Destroy() {
-    rwh_->set_paint_observer(NULL);
-  }
-
-  virtual void RenderWidgetHostWillPaint(RenderWidgetHost* rwh) {}
-
-  virtual void RenderWidgetHostDidPaint(RenderWidgetHost* rwh);
+  void Observe(NotificationType type,
+      const NotificationSource& source,

[brettw, 2011/01/03 19:48:30]

Indent these two args to the first one.

[DaveMoore, 2011/01/07 19:04:05]

N/A
On 2011/01/03 19:48:30, brettw wrote:

+      const NotificationDetails& details);
 
  private:
   TabContentsDelegateImpl* delegate_;
-  RenderWidgetHost* rwh_;
+  NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(PaintObserverImpl);
 };
@@ -415,8 +412,8 @@ class InstantLoader::TabContentsDelegateImpl : public TabContentsDelegate {
   // If the PaintObserver is non-null Destroy is invoked on it.
   void DestroyPaintObserver() {
     if (paint_observer_) {
-      paint_observer_->Destroy();
-      // Destroy should result in invoking PaintObserverDestroyed and NULLing
+      delete paint_observer_;
+      // delete should result in invoking PaintObserverDestroyed and NULLing
       // out paint_observer_.
       DCHECK(!paint_observer_);
     }
@@ -452,16 +449,20 @@ InstantLoader::PaintObserverImpl::~PaintObserverImpl() {
   delegate_->PaintObserverDestroyed(this);
 }
 
-void InstantLoader::PaintObserverImpl::RenderWidgetHostDidPaint(
-    RenderWidgetHost* rwh) {
-  TabContentsDelegateImpl* delegate = delegate_;
-  // Set the paint observer to NULL, which deletes us. Showing the preview may
-  // reset the paint observer, and delete us. By resetting the delegate first we
-  // know we've been deleted and can deal correctly.
-  rwh->set_paint_observer(NULL);
-  // WARNING: we've been deleted.
-  if (delegate)
-    delegate->PreviewPainted();
+void InstantLoader::PaintObserverImpl::Observe(NotificationType type,

[brettw, 2011/01/03 19:48:30]

Move this arg to the next line, indented 4 spaces.

[DaveMoore, 2011/01/07 19:04:05]

N/A
On 2011/01/03 19:48:30, brettw wrote:

+    const NotificationSource& source,
+    const NotificationDetails& details) {
+  if (type == NotificationType::RENDER_WIDGET_HOST_DID_PAINT) {
+    TabContentsDelegateImpl* delegate = delegate_;
+    // Delete outselves. Showing the preview may reload content. By resetting
+    // the observer first we know we've been deleted and can deal correctly.
+    delete this;
+    // WARNING: we've been deleted.
+    if (delegate)
+      delegate->PreviewPainted();
+  } else if (type == NotificationType::RENDER_WIDGET_HOST_DESTROYED) {
+    delete this;
+  }
 }
 
 InstantLoader::InstantLoader(InstantLoaderDelegate* delegate, TemplateURLID id)
@@ -628,11 +629,7 @@ TabContentsWrapper* InstantLoader::ReleasePreviewContents(
   if (preview_contents_.get()) {
     if (type != INSTANT_COMMIT_DESTROY)
       preview_tab_contents_delegate_->CommitHistory();
-    // Destroy the paint observer.
-    // RenderWidgetHostView may be null during shutdown.
     if (preview_contents_->tab_contents()->GetRenderWidgetHostView()) {
-      preview_contents_->tab_contents()->GetRenderWidgetHostView()->
-          GetRenderWidgetHost()->set_paint_observer(NULL);
 #if defined(OS_MACOSX)
       preview_contents_->tab_contents()->GetRenderWidgetHostView()->
           SetTakesFocusOnlyOnMouseDown(false);