Added popup that shows the new Back shortcut on Mac.

Implements BrowserWindowCocoa::ShowNewBackShortcutBubble to open the
Views implementation of this bubble (similar to how the fullscreen
bubble works on Mac).

BUG=610039

Review-Url: https://codereview.chromium.org/2017813004
Cr-Commit-Position: refs/heads/master@{#396759}
(cherry picked from commit d8fdd17)

Review URL: https://codereview.chromium.org/2020273003 .

Cr-Commit-Position: refs/branch-heads/2743@{crosswalk-project#160}
Cr-Branched-From: 2b3ae3b-refs/heads/master@{#394939}

chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.h

@@ -25,9 +25,10 @@ class BrowserWindow;
 class ExclusiveAccessBubbleViews;
 @class ExclusiveAccessBubbleWindowController;
 class GURL;
+class NewBackShortcutBubble;
 
 // Component placed into a browser window controller to manage communication
-// with the exclusive access bubble, which appears for events such as entering
+// with subtle notification bubbles, which appear for events such as entering
 // fullscreen.
 class ExclusiveAccessController : public ExclusiveAccessContext,
                                   public ui::AcceleratorProvider,
@@ -46,6 +47,9 @@ class ExclusiveAccessController : public ExclusiveAccessContext,
   // Shows the bubble once the NSWindow has received -windowDidEnterFullScreen:.
   void Show();
 
+  // Shows the new Back shortcut bubble.
+  void ShowNewBackShortcutBubble(bool forward);
+
   // Closes any open bubble.
   void Destroy();
 
@@ -100,6 +104,10 @@ class ExclusiveAccessController : public ExclusiveAccessContext,
   std::unique_ptr<ExclusiveAccessBubbleViews> views_bubble_;
   base::scoped_nsobject<ExclusiveAccessBubbleWindowController> cocoa_bubble_;
 
+  // This class also manages the new Back shortcut bubble (which functions the
+  // same way as ExclusiveAccessBubbleViews).
+  std::unique_ptr<NewBackShortcutBubble> new_back_shortcut_bubble_;
+
   // Used to keep track of the kShowFullscreenToolbar preference.
   PrefChangeRegistrar pref_registrar_;
 

chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm

@@ -13,6 +13,7 @@
 #include "chrome/browser/ui/exclusive_access/exclusive_access_manager.h"
 #include "chrome/browser/ui/status_bubble.h"
 #include "chrome/browser/ui/views/exclusive_access_bubble_views.h"
+#include "chrome/browser/ui/views/new_back_shortcut_bubble.h"
 #include "chrome/common/pref_names.h"
 #include "components/prefs/pref_service.h"
 #include "ui/base/cocoa/cocoa_base_utils.h"
@@ -50,6 +51,13 @@
   [cocoa_bubble_ showWindow];
 }
 
+void ExclusiveAccessController::ShowNewBackShortcutBubble(bool forward) {
+  if (new_back_shortcut_bubble_)
+    new_back_shortcut_bubble_->UpdateContent(forward);
+  else
+    new_back_shortcut_bubble_.reset(new NewBackShortcutBubble(this, forward));
+}
+
 void ExclusiveAccessController::Destroy() {
   views_bubble_.reset();
   [cocoa_bubble_ closeImmediately];

chrome/browser/ui/cocoa/browser_window_cocoa.mm

@@ -434,8 +434,9 @@ - (void)validateText:(NSString*)text {
 }
 
 void BrowserWindowCocoa::ShowNewBackShortcutBubble(bool forward) {
-  // TODO(mgiuca): Implement new back shortcut bubble Mac.
-  // https://crbug.com/610039.
+  ExclusiveAccessController* exclusive_access_controller =
+      [controller_ exclusiveAccessController];
+  exclusive_access_controller->ShowNewBackShortcutBubble(forward);
 }
 
 LocationBar* BrowserWindowCocoa::GetLocationBar() const {