Fix some grammar in content/common and content/public

content/public/browser/web_contents_delegate.h

Index: content/public/browser/web_contents_delegate.h
diff --git a/content/public/browser/web_contents_delegate.h b/content/public/browser/web_contents_delegate.h
index 2d1669cefc28e17b24371950a2890d15c097eef6..e6fe627e00d0f273cd9232e66e396e33db5760a2 100644
--- a/content/public/browser/web_contents_delegate.h
+++ b/content/public/browser/web_contents_delegate.h
@@ -178,7 +178,7 @@ class CONTENT_EXPORT WebContentsDelegate {
 
   // Tells us that we've finished firing this tab's beforeunload event.
   // The proceed bool tells us whether the user chose to proceed closing the
-  // tab. Returns true if the tab can continue on firing it's unload event.
+  // tab. Returns true if the tab can continue on firing its unload event.
   // If we're closing the entire browser, then we'll want to delay firing
   // unload events until all the beforeunload events have fired.
   virtual void BeforeUnloadFired(WebContents* tab,