Use correct snapshot for the tab transition animation on iPad

ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h

Index: ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h
diff --git a/ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h b/ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h
index 4f1baf1dbe4a85ff47ab886580d156d6e7c7d123..9fda6cddc9b425e7a84a3df4b408fd9995f7cf1b 100644
--- a/ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h
+++ b/ios/chrome/browser/ui/tab_switcher/tab_switcher_transition_context.h
@@ -9,6 +9,7 @@
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_tab_strip_placeholder_view.h"
 
+@class Tab;

[marq (ping after 24h), 2017/03/30 06:17:45]

This doesn't seem to be needed.

 @class TabModel;
 @class BrowserViewController;
 
@@ -27,9 +28,10 @@
 // Holds a snapshot view of the browser view controller's toolbar.
 @property(nonatomic, retain) UIView* toolbarSnapshotView;
 
-// Index of the selected tab in the browser view controller when the transition
-// context content was created.
-@property(nonatomic, assign) NSInteger initialSelectedTabIndex;
+// The tabID that was in the browser view controller when the transition context
+// content was created. Used to understand what might have changed in the model
+// when entering and leaving the tab switcher.
+@property(nonatomic, retain) NSString *initialTabID;

[marq (ping after 24h), 2017/03/30 06:17:45]

NSString* initialTabID;

 @end
 
 // A Tab switcher transition context holds the informations needed to compute