Modify the RenderThread to track the number of widgets...

chrome/renderer/render_widget.cc

 // Copyright (c) 2009 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 "chrome/renderer/render_widget.h"
 
 #include "base/gfx/point.h"
 #include "base/gfx/size.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 162 matching lines @@
 
   CompleteInit(parent);
 }
 
 void RenderWidget::OnClose() {
   if (closing_)
     return;
   closing_ = true;
 
   // Browser correspondence is no longer needed at this point.
-  if (routing_id_ != MSG_ROUTING_NONE)
+  if (routing_id_ != MSG_ROUTING_NONE) {
     render_thread_->RemoveRoute(routing_id_);
+    SetHidden(false);
+  }
 
   // If there is a Send call on the stack, then it could be dangerous to close
   // now.  Post a task that only gets invoked when there are no nested message
   // loops.
   MessageLoop::current()->PostNonNestableTask(FROM_HERE,
       NewRunnableMethod(this, &RenderWidget::Close));
 
   // Balances the AddRef taken when we called AddRoute.
   Release();
 }
 
 void RenderWidget::OnResize(const gfx::Size& new_size,
                             const gfx::Rect& resizer_rect) {
   // During shutdown we can just ignore this message.
   if (!webwidget_)
     return;
 
   // Remember the rect where the resize corner will be drawn.
   resizer_rect_ = resizer_rect;
 
   // TODO(darin): We should not need to reset this here.
-  is_hidden_ = false;
+  SetHidden(false);
   needs_repainting_on_restore_ = false;
 
   // We shouldn't be asked to resize to our current size.
   DCHECK(size_ != new_size);
   size_ = new_size;
 
   // We should not be sent a Resize message if we have not ACK'd the previous
   DCHECK(!next_paint_is_resize_ack());
 
   // When resizing, we want to wait to paint before ACK'ing the resize.  This
   // ensures that we only resize as fast as we can paint.  We only need to send
   // an ACK if we are resized to a non-empty rect.
   webwidget_->resize(new_size);
   if (!new_size.IsEmpty()) {
     DCHECK(!paint_rect_.IsEmpty());
 
     // This should have caused an invalidation of the entire view.  The damaged
     // rect could be larger than new_size if we are being made smaller.
     DCHECK_GE(paint_rect_.width(), new_size.width());
     DCHECK_GE(paint_rect_.height(), new_size.height());
 
     // We will send the Resize_ACK flag once we paint again.
     set_next_paint_is_resize_ack();
   }
 }
 
 void RenderWidget::OnWasHidden() {
   // Go into a mode where we stop generating paint and scrolling events.
-  is_hidden_ = true;
+  SetHidden(true);
 }
 
 void RenderWidget::OnWasRestored(bool needs_repainting) {
   // During shutdown we can just ignore this message.
   if (!webwidget_)
     return;
 
   // See OnWasHidden
-  is_hidden_ = false;
+  SetHidden(false);
 
   if (!needs_repainting && !needs_repainting_on_restore_)
     return;
   needs_repainting_on_restore_ = false;
 
   // Tag the next paint as a restore ack, which is picked up by DoDeferredPaint
   // when it sends out the next PaintRect message.
   set_next_paint_is_restore_ack();
 
   // Generate a full repaint.
@@ skipping 474 matching lines @@
   gfx::Rect repaint_rect(size_to_paint.width(), size_to_paint.height());
   didInvalidateRect(repaint_rect);
 }
 
 void RenderWidget::OnSetTextDirection(WebTextDirection direction) {
   if (!webwidget_)
     return;
   webwidget_->setTextDirection(direction);
 }
 
+void RenderWidget::SetHidden(bool hidden) {
+  if (is_hidden_ == hidden)
+    return;
+
+  // The status has changed.  Tell the RenderThread about it.
+  is_hidden_ = hidden;
+  if (is_hidden_)
+    render_thread_->WidgetHidden();
+  else
+    render_thread_->WidgetRestored();
+}
+
 void RenderWidget::SetBackground(const SkBitmap& background) {
   background_ = background;
   // Generate a full repaint.
   didInvalidateRect(gfx::Rect(size_.width(), size_.height()));
 }
 
 bool RenderWidget::next_paint_is_resize_ack() const {
   return ViewHostMsg_PaintRect_Flags::is_resize_ack(next_paint_flags_);
 }
 
@@ skipping 105 matching lines @@
 
 void RenderWidget::CleanupWindowInPluginMoves(gfx::PluginWindowHandle window) {
   for (WebPluginGeometryVector::iterator i = plugin_window_moves_.begin();
        i != plugin_window_moves_.end(); ++i) {
     if (i->window == window) {
       plugin_window_moves_.erase(i);
       break;
     }
   }
 }