Check for NULL backing store before painting.

Backing store for a RenderWidgetHostViewViews can be NULL. So make sure the
backing store was allocated correctly before painting to it.

BUG=66375
TEST=TabRestoreUITest.RestoreWindowAndTab and TabRestoreUITest.RestoreWindow passes with touchui=1

Review URL: http://codereview.chromium.org/6050009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70904 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 17 insertions, 10 deletions

diff --git a/chrome/browser/renderer_host/backing_store_manager.cc b/chrome/browser/renderer_host/backing_store_manager.cc
index 755a772..d9a273a 100644
--- a/chrome/browser/renderer_host/backing_store_manager.cc
+++ b/chrome/browser/renderer_host/backing_store_manager.cc
@@ -148,7 +148,8 @@ BackingStore* CreateBackingStore(RenderWidgetHost* host,
     cache = small_cache;
   }
   BackingStore* backing_store = host->AllocBackingStore(backing_store_size);
-  cache->Put(host, backing_store);
+  if (backing_store)
+    cache->Put(host, backing_store);
   return backing_store;
 }
 
@@ -203,14 +204,14 @@ void BackingStoreManager::PrepareBackingStore(
     // don't have a previous snapshot.
     if (bitmap_rect.size() != backing_store_size ||
         bitmap_rect.x() != 0 || bitmap_rect.y() != 0 ||
-        ComputeTotalArea(copy_rects) != backing_store_size.GetArea()) {
+        ComputeTotalArea(copy_rects) != backing_store_size.GetArea() ||
+        !(backing_store = CreateBackingStore(host, backing_store_size))) {
       DCHECK(needs_full_paint != NULL);
       *needs_full_paint = true;
       // Makes no sense to paint the transport dib if we are going
       // to request a full paint.
       return;
     }
-    backing_store = CreateBackingStore(host, backing_store_size);
   }
 
   backing_store->PaintToBackingStore(host->process(), bitmap,
diff --git a/chrome/browser/renderer_host/render_widget_host_view_views.cc b/chrome/browser/renderer_host/render_widget_host_view_views.cc
index a8049cf..3e70816 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_views.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_views.cc
@@ -324,12 +324,15 @@ bool RenderWidgetHostViewViews::IsPopup() {
 
 BackingStore* RenderWidgetHostViewViews::AllocBackingStore(
     const gfx::Size& size) {
+  gfx::NativeView nview = GetInnerNativeView();
+  if (!nview)
+    return NULL;
   return new BackingStoreX(host_, size,
-                           x11_util::GetVisualFromGtkWidget(native_view()),
-                           gtk_widget_get_visual(native_view())->depth);
+                           x11_util::GetVisualFromGtkWidget(nview),
+                           gtk_widget_get_visual(nview)->depth);
 }
 
-gfx::NativeView RenderWidgetHostViewViews::native_view() const {
+gfx::NativeView RenderWidgetHostViewViews::GetInnerNativeView() const {
   // TODO(sad): Ideally this function should be equivalent to GetNativeView, and
   // WidgetGtk-specific function call should not be necessary.
   views::WidgetGtk* widget = static_cast<views::WidgetGtk*>(GetWidget());
@@ -365,7 +368,7 @@ void RenderWidgetHostViewViews::Paint(gfx::Canvas* canvas) {
     return;
   }
 
-  GdkWindow* window = native_view()->window;
+  GdkWindow* window = GetInnerNativeView()->window;
   DCHECK(!about_to_validate_and_paint_);
 
   // TODO(anicolao): get the damage somehow
@@ -593,7 +596,7 @@ void RenderWidgetHostViewViews::WillLoseFocus() {
 void RenderWidgetHostViewViews::ShowCurrentCursor() {
   // The widget may not have a window. If that's the case, abort mission. This
   // is the same issue as that explained above in Paint().
-  if (!native_view() || !native_view()->window)
+  if (!GetInnerNativeView() || !GetInnerNativeView()->window)
     return;
 
   native_cursor_ = current_cursor_.GetNativeCursor();
diff --git a/chrome/browser/renderer_host/render_widget_host_view_views.h b/chrome/browser/renderer_host/render_widget_host_view_views.h
index 8a582a7..2aa9cf7 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_views.h
+++ b/chrome/browser/renderer_host/render_widget_host_view_views.h
@@ -43,6 +43,7 @@ class RenderWidgetHostViewViews : public RenderWidgetHostView,
   virtual void DidBecomeSelected();
   virtual void WasHidden();
   virtual void SetSize(const gfx::Size& size);
+  virtual gfx::NativeView GetNativeView();
   virtual void MovePluginWindows(
       const std::vector<webkit::npapi::WebPluginGeometry>& moves);
   virtual void Focus();
@@ -75,8 +76,10 @@ class RenderWidgetHostViewViews : public RenderWidgetHostView,
   virtual bool ContainsNativeView(gfx::NativeView native_view) const;
   virtual void AcceleratedCompositingActivated(bool activated);
 
-  gfx::NativeView native_view() const;
-  virtual gfx::NativeView GetNativeView();
+  // On some systems, there can be two native views, where an outer native view
+  // contains the inner native view (e.g. when using GTK+). This returns the
+  // inner view. This can return NULL when it's not attached to a view.
+  gfx::NativeView GetInnerNativeView() const;
 
   virtual void Paint(gfx::Canvas* canvas);