Add hints for potential overlay promotion on android.

cc/resources/texture_mailbox.h

Index: cc/resources/texture_mailbox.h
diff --git a/cc/resources/texture_mailbox.h b/cc/resources/texture_mailbox.h
index 4f8065d9de369070c61c07a93d2a6d9e66b91093..700f18683bc4a3c984151d0d394f5679f3808d57 100644
--- a/cc/resources/texture_mailbox.h
+++ b/cc/resources/texture_mailbox.h
@@ -74,11 +74,24 @@ class CC_EXPORT TextureMailbox {
   SharedBitmap* shared_bitmap() const { return shared_bitmap_; }
   size_t SharedMemorySizeInBytes() const;
 
+#if defined(OS_ANDROID)
+  bool is_backed_by_surface_texture() const {
+    return is_backed_by_surface_texture_;
+  }
+
+  void set_is_backed_by_surface_texture(bool value) {
+    is_backed_by_surface_texture_ = value;
+  }
+#endif
+
  private:
   gpu::MailboxHolder mailbox_holder_;
   SharedBitmap* shared_bitmap_;
   gfx::Size size_in_pixels_;
   bool is_overlay_candidate_;
+#if defined(OS_ANDROID)
+  bool is_backed_by_surface_texture_;
+#endif
   bool secure_output_only_;
   bool nearest_neighbor_;
   gfx::ColorSpace color_space_;