Add metrics to keep track of the tab activate/deactivate cycle

chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h

Index: chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h
diff --git a/chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h b/chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h
index 878c252bc8a927eaec864cdb7399964d68312c07..69a4b96300e4bbc5776072fd14066b606405af13 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h
+++ b/chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h
@@ -27,7 +27,8 @@ class TabStripModelObserverBridge : public TabStripModelObserver {
   ~TabStripModelObserverBridge() override;
 
   // Overridden from TabStripModelObserver
-  void TabInsertedAt(content::WebContents* contents,
+  void TabInsertedAt(TabStripModel* tab_strip_model,
+                     content::WebContents* contents,
                      int index,
                      bool foreground) override;
   void TabClosingAt(TabStripModel* tab_strip_model,
@@ -51,7 +52,8 @@ class TabStripModelObserverBridge : public TabStripModelObserver {
                      content::WebContents* old_contents,
                      content::WebContents* new_contents,
                      int index) override;
-  void TabPinnedStateChanged(content::WebContents* contents,
+  void TabPinnedStateChanged(TabStripModel* tab_strip_model,
+                             content::WebContents* contents,
                              int index) override;
   void TabStripEmpty() override;