rollback of weak/strong reference in MDCThumbTrack

Summary: This reverts commit 77e79d6.

Test Plan: revert-hammer

Reviewers:

Subscribers:

# Tip: Write "Fixes T123" in your summary to automatically close the
# corresponding task when this change lands.

Author: randallli

components/Switch/Switch.xcodeproj/project.pbxproj

@@ -423,7 +423,6 @@
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
-				CLANG_WARN_OBJC_REPEATED_USE_OF_WEAK = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -468,7 +467,6 @@
 				CLANG_WARN_EMPTY_BODY = YES;
 				CLANG_WARN_ENUM_CONVERSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
-				CLANG_WARN_OBJC_REPEATED_USE_OF_WEAK = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -501,7 +499,6 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.google.Switch;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				WARNING_CFLAGS = "";
 			};
 			name = Debug;
 		};
@@ -513,7 +510,6 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.google.Switch;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				WARNING_CFLAGS = "";
 			};
 			name = Release;
 		};

components/private/ThumbTrack/src/MDCThumbTrack.m

@@ -611,21 +611,19 @@ - (void)setValueFromThumbPosition:(CGPoint)position isTap:(BOOL)isTap {
   } else {
     value = [self valueForThumbPosition:position];
   }
-  __strong typeof(_delegate) strongDelegate = _delegate;
-  if ([strongDelegate respondsToSelector:@selector(thumbTrack:willAnimateToValue:)]) {
-    [strongDelegate thumbTrack:self willAnimateToValue:value];
+  __weak MDCThumbTrack *weakSelf = self;
+  if ([_delegate respondsToSelector:@selector(thumbTrack:willAnimateToValue:)]) {
+    [_delegate thumbTrack:self willAnimateToValue:value];
   }
-  __weak typeof(self) weakSelf = self;
   [self setValue:value
            animated:YES
       userGenerated:YES
          completion:^{
-           __strong typeof(weakSelf) strongSelf = weakSelf;
-           __strong typeof(strongSelf->_delegate) strongDelegate = strongSelf->_delegate;
+           MDCThumbTrack *strongSelf = weakSelf;
            [strongSelf sendDiscreteChangeAction];
-           if (strongSelf && [strongDelegate
+           if (strongSelf && [strongSelf->_delegate
                                  respondsToSelector:@selector(thumbTrack:didAnimateToValue:)]) {
-             [strongDelegate thumbTrack:strongSelf didAnimateToValue:value];
+             [strongSelf->_delegate thumbTrack:weakSelf didAnimateToValue:value];
            }
          }];
 }