Reducing CPU cycles of hidden/minimized browser windows

content/browser/web_contents/web_contents_view_aura.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/metrics/histogram.h"
@@ skipping 80 matching lines @@
   return mode == (base::i18n::IsRTL() ? OVERSCROLL_EAST : OVERSCROLL_WEST) &&
          controller.CanGoForward();
 }
 
 bool ShouldNavigateBack(const NavigationController& controller,
                         OverscrollMode mode) {
   return mode == (base::i18n::IsRTL() ? OVERSCROLL_WEST : OVERSCROLL_EAST) &&
          controller.CanGoBack();
 }
 
+// Update the |web contents| to be |visible|.
+void UpdateWebContentsVisibility(WebContentsImpl* web_contents, bool visible) {
+  if (visible) {
+    if (!web_contents->should_normally_be_visible())
+      web_contents->WasShown();
+  } else {
+    if (web_contents->should_normally_be_visible())
+      web_contents->WasHidden();
+  }
+}
+
 RenderWidgetHostViewAura* ToRenderWidgetHostViewAura(
     RenderWidgetHostView* view) {
   if (!view || RenderViewHostFactory::has_factory())
     return NULL;  // Can't cast to RenderWidgetHostViewAura in unit tests.
   RenderProcessHostImpl* process = static_cast<RenderProcessHostImpl*>(
       view->GetRenderWidgetHost()->GetProcess());
   if (process->IsGuest())
     return NULL;
   return static_cast<RenderWidgetHostViewAura*>(view);
 }
@@ skipping 600 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // WebContentsViewAura, private:
 
 WebContentsViewAura::~WebContentsViewAura() {
   if (!window_)
     return;
 
   window_observer_.reset();
+  window_->RemoveObserver(this);
 
   // Window needs a valid delegate during its destructor, so we explicitly
   // delete it here.
   window_.reset();
 }
 
 void WebContentsViewAura::SetupOverlayWindowForTesting() {
   if (navigation_overlay_)
     navigation_overlay_->SetupForTesting();
 }
@@ skipping 307 matching lines @@
   // NOTE: we ignore |initial_size| since in some cases it's wrong (such as
   // if the bookmark bar is not shown and you create a new tab). The right
   // value is set shortly after this, so its safe to ignore.
 
   aura::Env::CreateInstance(true);
   window_.reset(new aura::Window(this));
   window_->set_owned_by_parent(false);
   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
     // hierarchies are built before they're attached to a Widget. (See
     // views::WebView as an example; GetWidget() returns NULL at the point
     // where we are created.)
     //
     // It should be OK to not set a default parent since such users will
     // explicitly add this WebContentsViewAura to their tree after they create
     // us.
@@ skipping 362 matching lines @@
   // virtual functions to be called (e.g. OnImplicitAnimationsCompleted()). So
   // destroy the overscroll window here.
   navigation_overlay_.reset();
   overscroll_window_.reset();
 }
 
 void WebContentsViewAura::OnWindowDestroyed(aura::Window* window) {
 }
 
 void WebContentsViewAura::OnWindowTargetVisibilityChanged(bool visible) {
-  if (visible)
-    web_contents_->WasShown();
-  else
-    web_contents_->WasHidden();
 }
 
 bool WebContentsViewAura::HasHitTestMask() const {
   return false;
 }
 
 void WebContentsViewAura::GetHitTestMask(gfx::Path* mask) const {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 102 matching lines @@
   web_contents_->GetRenderViewHost()->DragTargetDrop(
       event.location(),
       gfx::Screen::GetScreenFor(GetNativeView())->GetCursorScreenPoint(),
       ConvertAuraEventFlagsToWebInputEventModifiers(event.flags()));
   if (drag_dest_delegate_)
     drag_dest_delegate_->OnDrop();
   current_drop_data_.reset();
   return ConvertFromWeb(current_drag_op_);
 }
 
+void WebContentsViewAura::OnWindowParentChanged(aura::Window* window,
+                                                aura::Window* parent) {
+  // On Windows we will get called with a parent of NULL as part of the shut
+  // down process. As such we do only change the visibility when a parent gets
+  // set.
+  if (parent)
+    UpdateWebContentsVisibility(web_contents_, window->IsVisible());
+}
+
+void WebContentsViewAura::OnWindowVisibilityChanged(aura::Window* window,
+                                                    bool visible) {
+  // Ignore any visibility changes in the hierarchy below.
+  if (window != window_.get() && window_->Contains(window))
+    return;
+
+  UpdateWebContentsVisibility(web_contents_, visible);
+}
+
 }  // namespace content