Add null check to InfoBarLayout.setIsUsingBigIcon to avoid NPE.

It's possible for us to get a null icon from getInstantAppLaunchData, so
perform a null check before using the icon in InfoBarLayout.

BUG=731801

Review-Url: https://codereview.chromium.org/2936703002
Cr-Commit-Position: refs/heads/master@{#478787}

chrome/android/java/src/org/chromium/chrome/browser/infobar/InfoBarLayout.java

@@ -251,6 +251,8 @@ public final class InfoBarLayout extends ViewGroup implements View.OnClickListen
      * Adjusts styling to account for the big icon layout.
      */
     public void setIsUsingBigIcon() {
+        if (mIconView == null) return;
+
         LayoutParams lp = (LayoutParams) mIconView.getLayoutParams();
         lp.width = mBigIconSize;
         lp.height = mBigIconSize;