[wip] Introduce SiteInstanceKeepAlive.

content/browser/frame_host/navigation_entry_screenshot_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/navigation_entry_screenshot_manager.h"
 
 #include "base/command_line.h"
 #include "base/threading/worker_pool.h"
 #include "content/browser/frame_host/navigation_controller_impl.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
+#include "content/public/browser/site_instance.h"
 #include "content/public/common/content_switches.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/effects/SkLumaColorFilter.h"
 #include "ui/gfx/codec/png_codec.h"
 
 namespace {
 
 // Minimum delay between taking screenshots.
 const int kMinScreenshotIntervalMS = 1000;
@@ skipping 103 matching lines @@
         owner_->GetEntryAtIndex(i)));
   }
   DCHECK_EQ(GetScreenshotCount(), 0);
 }
 
 void NavigationEntryScreenshotManager::TakeScreenshotImpl(
     RenderViewHost* host,
     NavigationEntryImpl* entry) {
   DCHECK(host && host->GetView());
   DCHECK(entry);
+  scoped_refptr<SiteInstanceImpl> site_instance(
+      static_cast<SiteInstanceImpl*>(host->GetSiteInstance()));
+  scoped_ptr<SiteInstanceKeepAlive> keep_alive(

[mfomitchev, 2014/02/14 16:21:36]

Why not just keep_alive = site_instance->AcquireKeepAlive()? AcquireKeepAlive()
already returns a scoped_ptr..

+      site_instance->AcquireKeepAlive());
   host->CopyFromBackingStore(gfx::Rect(),
       host->GetView()->GetViewBounds().size(),
       base::Bind(&NavigationEntryScreenshotManager::OnScreenshotTaken,
                  screenshot_factory_.GetWeakPtr(),
-                 entry->GetUniqueID()));
+                 entry->GetUniqueID(),
+                 base::Passed(&keep_alive)));
 }
 
 void NavigationEntryScreenshotManager::SetMinScreenshotIntervalMS(
     int interval_ms) {
   DCHECK_GE(interval_ms, 0);
   min_screenshot_interval_ms_ = interval_ms;
 }
 
-void NavigationEntryScreenshotManager::OnScreenshotTaken(int unique_id,
-                                                     bool success,
-                                                     const SkBitmap& bitmap) {
+void NavigationEntryScreenshotManager::OnScreenshotTaken(
+    int unique_id,
+    scoped_ptr<SiteInstanceKeepAlive> site_instance,

[mfomitchev, 2014/02/14 16:21:36]

rename this to keep_alive?

+    bool success,
+    const SkBitmap& bitmap) {
+  site_instance.reset();

[mfomitchev, 2014/02/14 16:21:36]

The biggest question for me is whether this will guarantee that everything will
eventually get destroyed properly. I played around with this fix a bit, and RWH
and RFH don't seem to get destroyed after the navigation completes, at least not
right away.

   NavigationEntryImpl* entry = NULL;
   int entry_count = owner_->GetEntryCount();
   for (int i = 0; i < entry_count; ++i) {
     NavigationEntry* iter = owner_->GetEntryAtIndex(i);
     if (iter->GetUniqueID() == unique_id) {
       entry = NavigationEntryImpl::FromNavigationEntry(iter);
       break;
     }
   }
 
@@ skipping 121 matching lines @@
         owner_->GetEntryAtIndex(forward));
     if (ClearScreenshot(entry))
       --screenshot_count;
     ++forward;
   }
   CHECK_GE(screenshot_count, 0);
   CHECK_LE(screenshot_count, kMaxScreenshots);
 }
 
 }  // namespace content