Remove unnecessary explicit keyword in ExclusiveAccessBubble class

BUG=none

Review URL: https://codereview.chromium.org/1808943002

Cr-Commit-Position: refs/heads/master@{#381654}

chrome/browser/ui/exclusive_access/exclusive_access_bubble.h

@@ -30,9 +30,9 @@ class Rect;
 //   has elapsed, the next user input re-displays the bubble.
 class ExclusiveAccessBubble : public gfx::AnimationDelegate {
  public:
-  explicit ExclusiveAccessBubble(ExclusiveAccessManager* manager,
-                                 const GURL& url,
-                                 ExclusiveAccessBubbleType bubble_type);
+  ExclusiveAccessBubble(ExclusiveAccessManager* manager,
+                        const GURL& url,
+                        ExclusiveAccessBubbleType bubble_type);
   ~ExclusiveAccessBubble() override;
 
   // Informs the ExclusiveAccessBubble of some user input, which may update