Added notification when user presses backspace to use new shortcut.

chrome/browser/ui/views/frame/browser_view.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/frame/browser_view.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 960 matching lines @@
 
 void BrowserView::UpdateExclusiveAccessExitBubbleContent(
     const GURL& url,
     ExclusiveAccessBubbleType bubble_type) {
   // Immersive mode has no exit bubble because it has a visible strip at the
   // top that gives the user a hover target.
   // TODO(jamescook): Figure out what to do with mouse-lock.
   if (bubble_type == EXCLUSIVE_ACCESS_BUBBLE_TYPE_NONE ||
       ShouldUseImmersiveFullscreenForUrl(url)) {
     exclusive_access_bubble_.reset();
-  } else if (exclusive_access_bubble_.get()) {
+    return;
+  }
+
+  // Hide the backspace shortcut bubble, to avoid overlapping.
+  new_back_shortcut_bubble_.reset();
+
+  if (exclusive_access_bubble_) {
     exclusive_access_bubble_->UpdateContent(url, bubble_type);
-  } else {
-    exclusive_access_bubble_.reset(
-        new ExclusiveAccessBubbleViews(this, url, bubble_type));
+    return;
   }
+
+  exclusive_access_bubble_.reset(
+      new ExclusiveAccessBubbleViews(this, url, bubble_type));
 }
 
 void BrowserView::OnExclusiveAccessUserInput() {
   if (exclusive_access_bubble_.get())
     exclusive_access_bubble_->OnUserInput();
 }
 
 bool BrowserView::ShouldHideUIForFullscreen() const {
   // Immersive mode needs UI for the slide-down top panel.
   if (immersive_mode_controller_->IsEnabled())
     return false;
 
   return IsFullscreen();
 }
 
 bool BrowserView::IsFullscreen() const {
   return frame_->IsFullscreen();
 }
 
 bool BrowserView::IsFullscreenBubbleVisible() const {
   return exclusive_access_bubble_ != nullptr;
 }
 
+void BrowserView::ShowNewBackShortcutBubble(bool forward) {
+  // Hide the exclusive access bubble, to avoid overlapping.
+  exclusive_access_bubble_.reset();
+
+  if (new_back_shortcut_bubble_) {
+    new_back_shortcut_bubble_->UpdateContent(forward);
+    return;
+  }
+
+  new_back_shortcut_bubble_.reset(new NewBackShortcutBubble(this, forward));

[Peter Kasting, 2016/05/24 23:35:08]

Nit: Shorter:

  if (new_back_shortcut_bubble_)
    new_back_shortcut_bubble_->UpdateContent(forward);
  else
    new_back_shortcut_bubble_.reset(new NewBackShortcutBubble(this, forward));

(This is structured how UpdateExclusiveAccessExitBubbleContent() used to work as
well; I kind of like this structure, but I assume you had some good reason for
changing it?)

[Matt Giuca, 2016/05/26 04:37:34]

Well there's a general (unwritten) rule in Chromium to prefer early return where
possible. (I've had some reviewers demand this, in fact.) But I'm happy either
way. Changing it back.

[Peter Kasting, 2016/05/26 05:19:40]

Huh, really?  I ask for early returns in cases where it shortens code or allows
unindenting large blocks, but I haven't really encountered a general push for
early returns outside that.

[Matt Giuca, 2016/05/26 06:05:39]

Oh OK. Well I think some people take the "no else after return" rule a bit far
and extrapolate it to "prefer if (x) { ...; return; } ... over if (x) { ... }
else { ... }." Hasn't come up for awhile.

+}
+
 void BrowserView::RestoreFocus() {
   WebContents* selected_web_contents = GetActiveWebContents();
   if (selected_web_contents)
     selected_web_contents->RestoreFocus();
 }
 
 void BrowserView::FullscreenStateChanged() {
   CHECK(!IsFullscreen());
   ProcessFullscreen(false, GURL(), EXCLUSIVE_ACCESS_BUBBLE_TYPE_NONE);
 }
@@ skipping 1605 matching lines @@
 }
 
 extensions::ActiveTabPermissionGranter*
 BrowserView::GetActiveTabPermissionGranter() {
   content::WebContents* web_contents = GetActiveWebContents();
   if (!web_contents)
     return nullptr;
   return extensions::TabHelper::FromWebContents(web_contents)
       ->active_tab_permission_granter();
 }