[wip] Introduce SiteInstanceKeepAlive.

content/browser/frame_host/navigation_entry_screenshot_manager.h

Index: content/browser/frame_host/navigation_entry_screenshot_manager.h
diff --git a/content/browser/frame_host/navigation_entry_screenshot_manager.h b/content/browser/frame_host/navigation_entry_screenshot_manager.h
index 072d6fd4a7fe19a1111acdb6b2e5c6c470f92285..83b062beb185cfa7d76ae809014e03befc613751 100644
--- a/content/browser/frame_host/navigation_entry_screenshot_manager.h
+++ b/content/browser/frame_host/navigation_entry_screenshot_manager.h
@@ -6,6 +6,7 @@
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_SCREENSHOT_MANAGER_H_
 
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
@@ -18,6 +19,7 @@ class NavigationControllerImpl;
 class NavigationEntryImpl;
 class RenderViewHost;
 class ScreenshotData;
+class SiteInstanceKeepAlive;
 
 // NavigationEntryScreenshotManager takes care of taking image-captures for the
 // current navigation entry of a NavigationControllerImpl, and managing these
@@ -50,9 +52,14 @@ class CONTENT_EXPORT NavigationEntryScreenshotManager {
   // The callback invoked when taking the screenshot of the page is complete.
   // This sets the screenshot on the navigation entry.
   void OnScreenshotTaken(int unique_id,
+                         scoped_ptr<SiteInstanceKeepAlive> keep_alive,
                          bool success,
                          const SkBitmap& bitmap);
 
+  void OnScreenshotTakenInTest(int unique_id,

[sadrul, 2014/02/20 05:13:31]

This is to avoid exposing SiteInstanceKeepAlive out of
NavigationEntryScreenshotManager

+                               bool success,
+                               const SkBitmap& bitmap);
+
   // Returns the number of entries with screenshots.
   int GetScreenshotCount() const;