Revert of [Fallback icons] Change "explicit flow" interface so color hex strings don't use "#".

chrome/common/favicon/fallback_icon_url_parser.cc

Index: chrome/common/favicon/fallback_icon_url_parser.cc
diff --git a/chrome/common/favicon/fallback_icon_url_parser.cc b/chrome/common/favicon/fallback_icon_url_parser.cc
index 3f6105d4ba2087f38eed3e1d6fb70253aab1d969..418617f46fec37ecc6fc13fa3289667f45ccbaea 100644
--- a/chrome/common/favicon/fallback_icon_url_parser.cc
+++ b/chrome/common/favicon/fallback_icon_url_parser.cc
@@ -7,25 +7,8 @@
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
-#include "base/strings/string_util.h"
 #include "third_party/skia/include/utils/SkParse.h"
 #include "ui/gfx/favicon_size.h"
-
-namespace {
-
-// Returns whether |color_str| is a valid CSS color in hex format if we prepend
-// '#', i.e., whether |color_str| matches /^[0-9A-Fa-f]{3,4,6,8}$/.
-bool IsHexColorString(const std::string& color_str) {
-  size_t len = color_str.length();
-  if (len != 3 && len != 4 && len != 6 && len != 8)
-    return false;
-  for (auto ch : color_str)
-    if (!IsHexDigit(ch))
-      return false;
-  return true;
-}
-
-}  // namespace
 
 namespace chrome {
 
@@ -93,23 +76,9 @@
 // static
 bool ParsedFallbackIconPath::ParseColor(const std::string& color_str,
                                         SkColor* color) {
-  // Exclude empty case. Also disallow '#' prefix since '#' is used to specify
-  // ref fragment in an URL, and so we want to avoid using it.
-  if (color_str.empty() || color_str[0] == '#')
-    return false;
-  // Force alpha = 0xFF since SkParse::FindColor() preserves unspecified alpha.
-  SkColor temp_color = SK_ColorWHITE;
-  // Prepend '#' if color hex string is given. This is unambiguous because no
-  // named color consists of leters 'a' to 'f' only.
-  const char* end = IsHexColorString(color_str) ?
-      SkParse::FindColor(("#" + color_str).c_str(), &temp_color) :
-      SkParse::FindColor(color_str.c_str(), &temp_color);
-  // Successful if FindColor() succeeds and |color_str| is completely consumed.
-  if (end && !*end) {
-    *color = temp_color;
-    return true;
-  }
-  return false;
+  const char* end = SkParse::FindColor(color_str.c_str(), color);
+  // Return true if FindColor() succeeds and |color_str| is entirely consumed.
+  return end && !*end;
 }
 
 }  // namespace chrome