Add cc::SurfaceInfo::is_valid()

cc/surfaces/surface_info.h

 // Copyright 2016 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.
 
 #ifndef CC_SURFACES_SURFACE_INFO_H_
 #define CC_SURFACES_SURFACE_INFO_H_
 
 #include "cc/surfaces/surface_id.h"
 #include "ui/gfx/geometry/size.h"
 
@@ skipping 11 matching lines @@
 class SurfaceInfo {
  public:
   SurfaceInfo() = default;
   SurfaceInfo(const SurfaceId& id,
               float device_scale_factor,
               const gfx::Size& size_in_pixels)
       : id_(id),
         device_scale_factor_(device_scale_factor),
         size_in_pixels_(size_in_pixels) {}
 
+  bool is_valid() const {
+    return id_.is_valid() && device_scale_factor_ != 0 &&
+           !size_in_pixels_.IsEmpty();
+  }
+
   bool operator==(const SurfaceInfo& info) const {
     return id_ == info.id() &&
            device_scale_factor_ == info.device_scale_factor() &&
            size_in_pixels_ == info.size_in_pixels();
   }
 
   bool operator!=(const SurfaceInfo& info) const { return !(*this == info); }
 
   const SurfaceId& id() const { return id_; }
   float device_scale_factor() const { return device_scale_factor_; }
   const gfx::Size& size_in_pixels() const { return size_in_pixels_; }
 
  private:
   friend struct mojo::StructTraits<mojom::SurfaceInfoDataView, SurfaceInfo>;
   friend struct IPC::ParamTraits<SurfaceInfo>;
 
   SurfaceId id_;
   float device_scale_factor_ = 1.f;
   gfx::Size size_in_pixels_;
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_INFO_H_