Surface synchronization: Introduce SurfaceInfo::ToString for debugging

I find myself printing out SurfaceInfo over and over again. This is a
quick CL to upstream this.

Bug: 672962
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: Ia1a4afbbb02f20e5cb6466fd5e381da192d713c1
Reviewed-on: https://chromium-review.googlesource.com/925681Reviewed-by: Saman Sami <samans@chromium.org>
Commit-Queue: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537783}

components/viz/common/BUILD.gn

@@ -133,6 +133,7 @@ viz_component("common") {
     "surfaces/parent_local_surface_id_allocator.h",
     "surfaces/surface_id.cc",
     "surfaces/surface_id.h",
+    "surfaces/surface_info.cc",
     "surfaces/surface_info.h",
     "switches.cc",
     "switches.h",

components/viz/common/surfaces/surface_info.cc

+// Copyright 2018 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.
+
+#include "components/viz/common/surfaces/surface_info.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace viz {
+
+std::string SurfaceInfo::ToString() const {
+  return base::StringPrintf("SurfaceInfo(%s, DeviceScaleFactor(%f), Size(%s))",
+                            id_.ToString().c_str(), device_scale_factor_,
+                            size_in_pixels_.ToString().c_str());
+}
+
+std::ostream& operator<<(std::ostream& out, const SurfaceInfo& surface_info) {
+  return out << surface_info.ToString();
+}
+
+}  // namespace viz

components/viz/common/surfaces/surface_info.h

@@ -6,6 +6,7 @@
 #define COMPONENTS_VIZ_COMMON_SURFACES_SURFACE_INFO_H_
 
 #include "components/viz/common/surfaces/surface_id.h"
+#include "components/viz/common/viz_common_export.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace IPC {
@@ -20,7 +21,7 @@ class SurfaceInfoDataView;
 }  // namespace mojom
 
 // This class contains information about the surface that is being embedded.
-class SurfaceInfo {
+class VIZ_COMMON_EXPORT SurfaceInfo {
  public:
   SurfaceInfo() = default;
   SurfaceInfo(const SurfaceId& id,
@@ -47,6 +48,8 @@ class SurfaceInfo {
   float device_scale_factor() const { return device_scale_factor_; }
   const gfx::Size& size_in_pixels() const { return size_in_pixels_; }
 
+  std::string ToString() const;
+
  private:
   friend struct mojo::StructTraits<mojom::SurfaceInfoDataView, SurfaceInfo>;
   friend struct IPC::ParamTraits<SurfaceInfo>;
@@ -56,6 +59,9 @@ class SurfaceInfo {
   gfx::Size size_in_pixels_;
 };
 
+VIZ_COMMON_EXPORT std::ostream& operator<<(std::ostream& out,
+                                           const SurfaceInfo& surface_info);
+
 }  // namespace viz
 
 #endif  // COMPONENTS_VIZ_COMMON_SURFACES_SURFACE_INFO_H_