Reducing CPU cycles of hidden/minimized browser windows

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index f134da3b24a005846f9d5709db22112628a86698..351b4297dd835efee579950fffc2fe110f3c6242 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -721,6 +721,7 @@ WebContentsViewAura::~WebContentsViewAura() {
 
   // Window needs a valid delegate during its destructor, so we explicitly
   // delete it here.
+  window_->RemoveObserver(this);
   window_.reset();
 }
 
@@ -1045,6 +1046,7 @@ void WebContentsViewAura::CreateView(
   window_->SetType(ui::wm::WINDOW_TYPE_CONTROL);
   window_->SetTransparent(false);
   window_->Init(aura::WINDOW_LAYER_NOT_DRAWN);
+  window_->AddObserver(this);
   aura::Window* root_window = context ? context->GetRootWindow() : NULL;
   if (root_window) {
     // There are places where there is no context currently because object
@@ -1555,4 +1557,26 @@ int WebContentsViewAura::OnPerformDrop(const ui::DropTargetEvent& event) {
   return ConvertFromWeb(current_drag_op_);
 }
 
+void WebContentsViewAura::OnWindowParentChanged(aura::Window* window,
+                                                aura::Window* parent) {
+  if (!parent || parent->IsVisible())

[sky, 2014/05/16 20:14:58]

I don't get why you're tracking visibility of the parent to determine whether
this is visible here (and below). I see your comment, but that doesn't explain.
What flash? What is causing the flast?

I also suspect your changes may invoke WasShow (or WasHidden) multiple times in
a row. I don't know that the rest of the code deals well with that.

Lastly, how a test?

+    web_contents_->WasShown();
+  else
+    web_contents_->WasHidden();
+}
+
+void WebContentsViewAura::OnWindowVisibilityChanged(aura::Window* window,
+                                                    bool visible) {
+  aura::Window* parent = window_->parent();
+  if (!parent)
+    return;
+
+  // Follow the visibility of the parent window since e.g. navigation
+  // operations could otherwise cause a flash.
+  if (parent->IsVisible())
+    web_contents_->WasShown();
+  else
+    web_contents_->WasHidden();
+}
+
 }  // namespace content