Support writing ObjC types to a LOG(…) stream.

Change-Id: I9ab020f86ff2781a6651ac82aae60c59b497e6ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1607440
Auto-Submit: Sidney San Martín <sdy@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Sidney San Martín <sdy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659060}

base/mac/foundation_util.h

@@ -397,5 +397,11 @@ BASE_EXPORT extern std::ostream& operator<<(std::ostream& o,
                                             const CFErrorRef err);
 BASE_EXPORT extern std::ostream& operator<<(std::ostream& o,
                                             const CFStringRef str);
+BASE_EXPORT extern std::ostream& operator<<(std::ostream& o, CFRange);
+
+#if defined(__OBJC__)
+BASE_EXPORT extern std::ostream& operator<<(std::ostream& o, id);
+BASE_EXPORT extern std::ostream& operator<<(std::ostream& o, NSRange);
+#endif
 
 #endif  // BASE_MAC_FOUNDATION_UTIL_H_

base/mac/foundation_util.mm

@@ -498,3 +498,15 @@ std::ostream& operator<<(std::ostream& o, const CFErrorRef err) {
   }
   return o;
 }
+
+std::ostream& operator<<(std::ostream& o, CFRange range) {
+  return o << NSStringFromRange(NSMakeRange(range.location, range.length));
+}
+
+std::ostream& operator<<(std::ostream& o, id obj) {
+  return obj ? o << [obj description].UTF8String : o << "(nil)";
+}
+
+std::ostream& operator<<(std::ostream& o, NSRange range) {
+  return o << NSStringFromRange(range);
+}

base/mac/foundation_util_unittest.mm

@@ -409,5 +409,24 @@ TEST(StringNumberConversionsTest, FormatNSInteger) {
   }
 }
 
+#define EXPECT_LOG_EQ(expected, val) \
+  EXPECT_EQ(expected, (std::ostringstream() << (val)).str())
+
+TEST(FoundationLoggingTest, ObjCObject) {
+  EXPECT_LOG_EQ("Hello, world!", @"Hello, world!");
+}
+
+TEST(FoundationLoggingTest, ObjCNil) {
+  EXPECT_LOG_EQ("(nil)", static_cast<id>(nil));
+}
+
+TEST(FoundationLoggingTest, CFRange) {
+  EXPECT_LOG_EQ("{0, 100}", CFRangeMake(0, 100));
+}
+
+TEST(FoundationLoggingTest, NSRange) {
+  EXPECT_LOG_EQ("{0, 100}", NSMakeRange(0, 100));
+}
+
 }  // namespace mac
 }  // namespace base