Adds kind-of-live thumbnail generation for a potential tab switcher.

chrome/browser/renderer_host/backing_store_mac.cc

Index: chrome/browser/renderer_host/backing_store_mac.cc
diff --git a/chrome/browser/renderer_host/backing_store_mac.cc b/chrome/browser/renderer_host/backing_store_mac.cc
index 569e3f656ed1dff5e41b53c2d1d99182b753b275..2395a6c318776d6ecdeae362e9127dd83a7c5121 100644
--- a/chrome/browser/renderer_host/backing_store_mac.cc
+++ b/chrome/browser/renderer_host/backing_store_mac.cc
@@ -10,8 +10,9 @@
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
-BackingStore::BackingStore(const gfx::Size& size)
-    : size_(size) {
+BackingStore::BackingStore(RenderWidgetHost* widget, const gfx::Size& size)
+    : render_widget_host_(widget),
+      size_(size) {
   if (!canvas_.initialize(size.width(), size.height(), true))
     SK_CRASH();
 }