Null init for ClickToCallSharingDialogController pointer.

Integration tests were reverted because of this error: https://chromium-review.googlesource.com/c/chromium/src/+/1727231

Bug: 982229
Change-Id: Id88be2768477a06320ba1f664cdc762c2865d765
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1728652
Commit-Queue: Himanshu Jaju <himanshujaju@chromium.org>
Reviewed-by: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682645}

chrome/browser/ui/views/sharing/click_to_call/click_to_call_icon_view.h

@@ -65,7 +65,7 @@ class ClickToCallIconView : public PageActionIconView {
   SkColor loader_color_;
   std::unique_ptr<gfx::ThrobAnimation> loading_animation_;
   bool show_error_ = false;
-  ClickToCallSharingDialogController* last_controller_;
+  ClickToCallSharingDialogController* last_controller_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(ClickToCallIconView);
 };