[Home] Check for null bottom sheet in BottomToolbarPhone#updateVisuals

BottomToolbarPhone#updateVisualsForToolbarState() is now called from
BottomToolbarPhone#onAttachedToWindow(). We have crash reports
indicating that for some users the bottom sheet is null when the toolbar
is attached to the window. Adding null checks.

BUG=769612

Change-Id: I6dc5e86851b8c054f50e798ac854fff0e3629d43
Reviewed-on: https://chromium-review.googlesource.com/690800Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505135}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/BottomToolbarPhone.java

@@ -334,7 +334,7 @@ public class BottomToolbarPhone extends ToolbarPhone {
 
     @Override
     public boolean isInTabSwitcherMode() {
-        return !mBottomSheet.isSheetOpen() && super.isInTabSwitcherMode();
+        return super.isInTabSwitcherMode() && (mBottomSheet == null || !mBottomSheet.isSheetOpen());
     }
 
     @Override
@@ -744,7 +744,7 @@ public class BottomToolbarPhone extends ToolbarPhone {
             mExpandButton.setTint(tint);
         }
 
-        if (mBottomSheet.isSheetOpen()) {
+        if (mBottomSheet != null && mBottomSheet.isSheetOpen()) {
             mShowMenuButtonWhenSheetOpen = mBottomSheet.isShowingNewTab();
             updateButtonsContainerVisibilityAndTranslation();
             updateMenuButtonClickableState();