Follow up from ARC conversion

Addressing the comments raised in https://codereview.chromium.org/2808873002/

BUG=none

Review-Url: https://codereview.chromium.org/2851713002
Cr-Commit-Position: refs/heads/master@{#467951}

ios/chrome/browser/ui/toolbar/toolbar_controller.mm

@@ -35,6 +35,10 @@
 #import "ios/shared/chrome/browser/ui/tools_menu/tools_menu_configuration.h"
 #import "ios/third_party/material_roboto_font_loader_ios/src/src/MaterialRobotoFontLoader.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using base::UserMetricsAction;
 using ios::material::TimingFunction;
 
@@ -76,10 +80,6 @@ NSString* const kToolbarShareButtonIdentifier =
 // Makes a two-element C array of CGRects as described above, one for each
 // device idiom.
 #define FRAME_PAIR(H) { IPHONE_FRAME(H), IPAD_FRAME(H) }
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
 // clang-format on
 
 const CGRect kToolbarFrame[INTERFACE_IDIOM_COUNT] = FRAME_PAIR(56);

ios/chrome/browser/ui/toolbar/web_toolbar_controller.mm

@@ -849,7 +849,7 @@ CGRect RectShiftedDownAndResizedForStatusBar(CGRect rect) {
 - (void)dismissTabHistoryPopup {
   if (!_tabHistoryPopupController)
     return;
-  TabHistoryPopupController* tempTHPC = _tabHistoryPopupController;
+  __block TabHistoryPopupController* tempTHPC = _tabHistoryPopupController;
   [tempTHPC containerView].userInteractionEnabled = NO;
   [tempTHPC dismissAnimatedWithCompletion:^{
     // Unpress the back/forward button by restoring the normal and
@@ -857,7 +857,7 @@ CGRect RectShiftedDownAndResizedForStatusBar(CGRect rect) {
     [self setImagesForNavButton:_backButton withTabHistoryVisible:NO];
     [self setImagesForNavButton:_forwardButton withTabHistoryVisible:NO];
     // Reference tempTHPC so the block retains it.
-    [tempTHPC self];
+    tempTHPC = nil;
   }];
   // reset _tabHistoryPopupController to prevent -applicationDidEnterBackground
   // from posting another kTabHistoryPopupWillHideNotification.