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

content/renderer/manifest/manifest_parser.h

Index: content/renderer/manifest/manifest_parser.h
diff --git a/content/renderer/manifest/manifest_parser.h b/content/renderer/manifest/manifest_parser.h
index 2c8d2076e33075824469ae3e04ead46d83515387..8be1d5d06cdc415b63df512ab943bbc3df803126 100644
--- a/content/renderer/manifest/manifest_parser.h
+++ b/content/renderer/manifest/manifest_parser.h
@@ -66,10 +66,10 @@ class CONTENT_EXPORT ManifestParser {
 
   // Helper function to parse colors present on a given |dictionary| in a given
   // field identified by its |key|.
-  // Returns the parsed color as an int64_t if any,
-  // Manifest::kInvalidOrMissingColor if the parsing failed.
-  int64_t ParseColor(const base::DictionaryValue& dictionary,
-                     const std::string& key);
+  // Returns the parsed color as Optional<SkColor>; if the parsing failed, the
+  // Optional<> will be empty.
+  base::Optional<SkColor> ParseColor(const base::DictionaryValue& dictionary,
+                                     const std::string& key);
 
   // Helper function to parse URLs present on a given |dictionary| in a given
   // field identified by its |key|. The URL is first parsed as a string then
@@ -171,15 +171,17 @@ class CONTENT_EXPORT ManifestParser {
 
   // Parses the 'theme_color' field of the manifest, as defined in:
   // http://w3c.github.io/manifest/#dfn-steps-for-processing-the-theme_color-member
-  // Returns the parsed theme color if any,
-  // Manifest::kInvalidOrMissingColor if the parsing failed.
-  int64_t ParseThemeColor(const base::DictionaryValue& dictionary);
+  // Returns the parsed theme color wrapped in an Optional<> if any, empty
+  // Optional<> if the parsing failed.
+  base::Optional<SkColor> ParseThemeColor(
+      const base::DictionaryValue& dictionary);
 
   // Parses the 'background_color' field of the manifest, as defined in:
   // http://w3c.github.io/manifest/#dfn-steps-for-processing-the-background_color-member
-  // Returns the parsed background color if any,
-  // Manifest::kInvalidOrMissingColor if the parsing failed.
-  int64_t ParseBackgroundColor(const base::DictionaryValue& dictionary);
+  // Returns the parsed background color wrapped in an Optional<> if any, empty
+  // Optional<> if the parsing failed.
+  base::Optional<SkColor> ParseBackgroundColor(
+      const base::DictionaryValue& dictionary);
 
   // Parses the 'gcm_sender_id' field of the manifest.
   // This is a proprietary extension of the Web Manifest specification.