Fix more ToolbarPhone texture capture issues

 - postInvalidate after exiting tab switcher. This ensures a new texture
   is captured immediately.
 - don't allow a texture to be captured while the NTP is scrolled.

BUG=922909,916561

Change-Id: I08de5bd7f6d948c1574ec17e7967fef2dcf5ed06
Reviewed-on: https://chromium-review.googlesource.com/c/1432372Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625414}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/top/ToolbarPhone.java

@@ -1527,7 +1527,7 @@ public class ToolbarPhone extends ToolbarLayout implements Invalidator.Client, O
             return true;
         }
         return !(mTabSwitcherState == TAB_SWITCHER || mTabSwitcherModeAnimation != null
-                || urlHasFocus() || mUrlFocusChangeInProgress);
+                || urlHasFocus() || mUrlFocusChangeInProgress || mNtpSearchBoxScrollPercent > 0);
     }
 
     @Override
@@ -1676,6 +1676,7 @@ public class ToolbarPhone extends ToolbarLayout implements Invalidator.Client, O
 
         // Request a texture update to ensure a texture is captured before the user
         // re-enters the tab switcher.
+        postInvalidate();
         mLayoutUpdateHost.requestUpdate();
     }