Add heuristics to limit showing of new backspace UI bubble.

chrome/browser/ui/browser_view_prefs.cc

Index: chrome/browser/ui/browser_view_prefs.cc
diff --git a/chrome/browser/ui/browser_view_prefs.cc b/chrome/browser/ui/browser_view_prefs.cc
index 3232859dfc2110e43a4e9da7c8916756ce13bd3b..c38a79ffe15966efe3ddc7dd24d49c75168cc2cc 100644
--- a/chrome/browser/ui/browser_view_prefs.cc
+++ b/chrome/browser/ui/browser_view_prefs.cc
@@ -36,9 +36,10 @@ void RegisterBrowserViewProfilePrefs(
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   custom_frame_default = ui::GetCustomFramePrefDefault();
 #endif
-
   registry->RegisterBooleanPref(prefs::kUseCustomChromeFrame,

[Matt Giuca, 2016/06/08 01:29:03]

nit: Any reason to delete the above line? If anything I think there should be a
blank line here but none between the two Register*Pref calls.

[Peter Kasting, 2016/06/09 19:49:31]

The code above is closely tied to this line: it's calculating the value to pass
to this function.  If we didn't need an ifdef, we'd have inlined that code into
this call.

Whereas this call and the one below have no relationship to each other; they're
for different prefs with different values.

[Matt Giuca, 2016/06/10 01:07:05]

Acknowledged.

                                 custom_frame_default);
+
+  registry->RegisterIntegerPref(prefs::kBackShortcutBubbleShownCount, 0);

[Matt Giuca, 2016/06/08 01:29:03]

I think we should have separate counters for the Back and Forward shortcuts.
Otherwise you could use up your 5 Back presses and never be taught the Forward
shortcut.

[Peter Kasting, 2016/06/09 19:49:31]

My instinct is that one counter for both is the way to go.

I asked Tyler to weigh in.  He also thought one counter would be best, noting
that the forward shortcut is pretty intuitive once one knows the back shortcut.

Neither of us feel violently about this, if you want to try to convince us
further.

[Matt Giuca, 2016/06/10 01:07:05]

Not particularly :)

 }
 
 void MigrateBrowserTabStripPrefs(PrefService* prefs) {