Avoid calling RWHVWin::GetBackingStore when accelerated compositing is enabled.

It's milliseconds expensive and it's not needed in this case.

Review URL: https://chromiumcodereview.appspot.com/10967027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@157915 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 16 deletions

diff --git a/content/browser/renderer_host/render_widget_host_view_win.cc b/content/browser/renderer_host/render_widget_host_view_win.cc
index 9f01a0d..955c49c 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.cc
+++ b/content/browser/renderer_host/render_widget_host_view_win.cc
@@ -1306,6 +1306,14 @@ void RenderWidgetHostViewWin::OnDestroy() {
 
 void RenderWidgetHostViewWin::OnPaint(HDC unused_dc) {
   TRACE_EVENT0("browser", "RenderWidgetHostViewWin::OnPaint");
+
+  // Grab the region to paint before creation of paint_dc since it clears the
+  // damage region.
+  base::win::ScopedGDIObject<HRGN> damage_region(CreateRectRgn(0, 0, 0, 0));
+  GetUpdateRgn(damage_region, FALSE);
+
+  CPaintDC paint_dc(m_hWnd);
+
   if (!render_widget_host_)
     return;
 
@@ -1316,9 +1324,6 @@ void RenderWidgetHostViewWin::OnPaint(HDC unused_dc) {
   // do here is clear borders during resize.
   if (compositor_host_window_ &&
       render_widget_host_->is_accelerated_compositing_active()) {
-    // We initialize paint_dc here so that BeginPaint()/EndPaint()
-    // get called to validate the region.
-    CPaintDC paint_dc(m_hWnd);
     RECT host_rect, child_rect;
     GetClientRect(&host_rect);
     if (::GetClientRect(compositor_host_window_, &child_rect) &&
@@ -1330,6 +1335,12 @@ void RenderWidgetHostViewWin::OnPaint(HDC unused_dc) {
     return;
   }
 
+  if (accelerated_surface_.get() &&
+      render_widget_host_->is_accelerated_compositing_active()) {
+    AcceleratedPaint(paint_dc.m_hDC);
+    return;
+  }
+
   about_to_validate_and_paint_ = true;
   BackingStoreWin* backing_store = static_cast<BackingStoreWin*>(
       render_widget_host_->GetBackingStore(true));
@@ -1339,28 +1350,15 @@ void RenderWidgetHostViewWin::OnPaint(HDC unused_dc) {
   // changes and repaint them.
   about_to_validate_and_paint_ = false;
 
-  // Grab the region to paint before creation of paint_dc since it clears the
-  // damage region.
-  base::win::ScopedGDIObject<HRGN> damage_region(CreateRectRgn(0, 0, 0, 0));
-  GetUpdateRgn(damage_region, FALSE);
-
   if (compositor_host_window_ && hide_compositor_window_at_next_paint_) {
     ::ShowWindow(compositor_host_window_, SW_HIDE);
     hide_compositor_window_at_next_paint_ = false;
   }
 
-  CPaintDC paint_dc(m_hWnd);
-
   gfx::Rect damaged_rect(paint_dc.m_ps.rcPaint);
   if (damaged_rect.IsEmpty())
     return;
 
-  if (accelerated_surface_.get() &&
-      render_widget_host_->is_accelerated_compositing_active()) {
-    AcceleratedPaint(paint_dc.m_hDC);
-    return;
-  }
-
   if (backing_store) {
     gfx::Rect bitmap_rect(gfx::Point(), backing_store->size());