[WIP] Use Optional<SkColor> instead of int64 for colors in Manifest.

content/public/common/manifest.h

Index: content/public/common/manifest.h
diff --git a/content/public/common/manifest.h b/content/public/common/manifest.h
index 71e8f60599f02df7bc2969871f226eb550be0cc3..394812530a942043a24b00f43374a3849df0aae9 100644
--- a/content/public/common/manifest.h
+++ b/content/public/common/manifest.h
@@ -10,10 +10,12 @@
 
 #include <vector>
 
+#include "base/optional.h"
 #include "base/strings/nullable_string16.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/WebDisplayMode.h"
 #include "third_party/WebKit/public/platform/modules/screen_orientation/WebScreenOrientationLockType.h"
+#include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/geometry/size.h"
 #include "url/gurl.h"
 
@@ -106,19 +108,13 @@ struct CONTENT_EXPORT Manifest {
   // or there is a parsing failure.
   bool prefer_related_applications;
 
-  // This is a 64 bit integer because we need to represent an error state. The
-  // color itself should only be 32 bits long if the value is not
-  // kInvalidOrMissingColor and can be safely cast to SkColor if is valid.
-  // Set to kInvalidOrMissingColor if parsing failed or field is not
-  // present.
-  int64_t theme_color;
+  // The Optional is empty if no value was present or if it was invalid. It is
+  // a valid SkColor otherwise.
+  base::Optional<SkColor> theme_color;
 
-  // This is a 64 bit integer because we need to represent an error state. The
-  // color itself should only be 32 bits long if the value is not
-  // kInvalidOrMissingColor and can be safely cast to SkColor if is valid.
-  // Set to kInvalidOrMissingColor if parsing failed or field is not
-  // present.
-  int64_t background_color;
+  // The Optional is empty if no value was present or if it was invalid. It is
+  // a valid SkColor otherwise.
+  base::Optional<SkColor> background_color;
 
   // This is a proprietary extension of the web Manifest, double-check that it
   // is okay to use this entry.
@@ -132,10 +128,6 @@ struct CONTENT_EXPORT Manifest {
   // IPC. The renderer process should truncate the strings before sending the
   // Manifest and the browser process must do the same when receiving it.
   static const size_t kMaxIPCStringLength;
-
-  // Constant representing an invalid color. Set to a value outside the
-  // range of a 32-bit integer.
-  static const int64_t kInvalidOrMissingColor;
 };
 
 } // namespace content