Add heuristics to limit showing of new backspace UI bubble.

chrome/browser/ui/views/new_back_shortcut_bubble.cc

Index: chrome/browser/ui/views/new_back_shortcut_bubble.cc
diff --git a/chrome/browser/ui/views/new_back_shortcut_bubble.cc b/chrome/browser/ui/views/new_back_shortcut_bubble.cc
index c43d3f46e3feee4597459bc9ccd1ece0f25df03a..c7529d26c28fbc9c46cb6cb0590d58a79aaf00b5 100644
--- a/chrome/browser/ui/views/new_back_shortcut_bubble.cc
+++ b/chrome/browser/ui/views/new_back_shortcut_bubble.cc
@@ -31,8 +31,7 @@ const int kShowDurationMs = 3800;
 }
 
 NewBackShortcutBubble::NewBackShortcutBubble(
-    ExclusiveAccessBubbleViewsContext* context,
-    bool forward)
+    ExclusiveAccessBubbleViewsContext* context)
     : bubble_view_context_(context),
       animation_(new gfx::SlideAnimation(this)),
       view_(new SubtleNotificationView(nullptr)),
@@ -40,7 +39,6 @@ NewBackShortcutBubble::NewBackShortcutBubble(
           bubble_view_context_->GetBubbleParentView(),
           view_,
           false)) {
-  UpdateContent(forward);
 }
 
 NewBackShortcutBubble::~NewBackShortcutBubble() {
@@ -50,6 +48,10 @@ NewBackShortcutBubble::~NewBackShortcutBubble() {
   base::MessageLoop::current()->DeleteSoon(FROM_HERE, popup_);
 }
 
+bool NewBackShortcutBubble::IsVisible() const {
+  return popup_->IsVisible();
+}
+
 void NewBackShortcutBubble::UpdateContent(bool forward) {
   // Note: The key names are parameters so that we can vary by operating system
   // or change the direction of the arrow as necessary (see
@@ -83,6 +85,11 @@ void NewBackShortcutBubble::UpdateContent(bool forward) {
                       &NewBackShortcutBubble::OnTimerElapsed);
 }
 
+void NewBackShortcutBubble::Hide() {
+  hide_timeout_.Stop();
+  OnTimerElapsed();
+}
+
 void NewBackShortcutBubble::AnimationProgressed(
     const gfx::Animation* animation) {
   int opacity = animation_->CurrentValueBetween(0, 255);