[CI] Add logging ToString to LayoutRectOutsets

LayoutRectOutsets appear in painting code and are otherwise cumbersome to log.

R=pdr@chromium.org

Change-Id: Iab1cb66b3692bf48250d896e0448dfbd8e3ee8ec
Reviewed-on: https://chromium-review.googlesource.com/1078938Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563030}

third_party/blink/renderer/platform/geometry/layout_rect_outsets.cc

@@ -32,6 +32,7 @@
 
 #include <algorithm>
 #include "third_party/blink/renderer/platform/wtf/assertions.h"
+#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
 
 namespace blink {
 
@@ -49,4 +50,16 @@ void LayoutRectOutsets::Unite(const LayoutRectOutsets& other) {
   left_ = std::max(left_, other.left_);
 }
 
+std::ostream& operator<<(std::ostream& ostream,
+                         const LayoutRectOutsets& outsets) {
+  return ostream << outsets.ToString();
+}
+
+String LayoutRectOutsets::ToString() const {
+  return String::Format(
+      "top %s; right %s; bottom %s; left %s", Top().ToString().Ascii().data(),
+      Right().ToString().Ascii().data(), Bottom().ToString().Ascii().data(),
+      Left().ToString().Ascii().data());
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/geometry/layout_rect_outsets.h

@@ -97,6 +97,8 @@ class PLATFORM_EXPORT LayoutRectOutsets {
            Bottom() == other.Bottom() && Left() == other.Left();
   }
 
+  String ToString() const;
+
  private:
   LayoutUnit top_;
   LayoutUnit right_;
@@ -145,6 +147,9 @@ inline LayoutRectOutsets EnclosingLayoutRectOutsets(
                            LayoutUnit::FromFloatCeil(rect.Left()));
 }
 
+PLATFORM_EXPORT std::ostream& operator<<(std::ostream&,
+                                         const LayoutRectOutsets&);
+
 }  // namespace blink
 
 #endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_GEOMETRY_LAYOUT_RECT_OUTSETS_H_