The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d013ba1d118e12de14e02c115417dfdfb925c831

commit d013ba1d118e12de14e02c115417dfdfb925c831
Author: Shakti Sahu <shaktisahu@chromium.org>
Date: Thu Aug 10 00:17:46 2017

In-product-help : Back button should dismiss IPH bubble

The in-product-help message gets dismissed only on touch. But if the
device back button is pressed and chrome navigates to the previous page,
the bubble is still there. I think the bubble should be dismissed in
that case.

Bug:  754071 
Change-Id: I311784d87759040bb7bb3c8ba076d84d80792eda
Reviewed-on: https://chromium-review.googlesource.com/588109
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493187}
[modify] https://crrev.com/d013ba1d118e12de14e02c115417dfdfb925c831/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
[modify] https://crrev.com/d013ba1d118e12de14e02c115417dfdfb925c831/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity.java
[modify] https://crrev.com/d013ba1d118e12de14e02c115417dfdfb925c831/chrome/android/java/src/org/chromium/chrome/browser/widget/textbubble/TextBubble.java