Ensure RenderViewHost is not shut down until a screenshot of the page is taken.

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"
@@ skipping 132 matching lines @@
                  entry->GetUniqueID()),
       preferred_format);
 }
 
 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,
+    bool success,
+    const SkBitmap& bitmap) {
   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;
     }
   }
 
   if (!entry) {
     LOG(ERROR) << "Invalid entry with unique id: " << unique_id;
     return;
   }
 
   if (!success || bitmap.empty() || bitmap.isNull()) {
-    if (!ClearScreenshot(entry))
-      OnScreenshotSet(entry);
+    ClearScreenshot(entry);
     return;
   }
 
   scoped_refptr<ScreenshotData> screenshot = new ScreenshotData();
   screenshot->EncodeScreenshot(
       bitmap,
       base::Bind(&NavigationEntryScreenshotManager::OnScreenshotEncodeComplete,
                  screenshot_factory_.GetWeakPtr(),
                  unique_id,
                  screenshot));
@@ skipping 24 matching lines @@
     }
   }
   if (!entry)
     return;
   entry->SetScreenshotPNGData(screenshot->data());
   OnScreenshotSet(entry);
 }
 
 void NavigationEntryScreenshotManager::OnScreenshotSet(
     NavigationEntryImpl* entry) {
-  if (entry->screenshot().get())
-    PurgeScreenshotsIfNecessary();
+  CHECK(entry->screenshot().get());
+  PurgeScreenshotsIfNecessary();
 }
 
 bool NavigationEntryScreenshotManager::ClearScreenshot(
     NavigationEntryImpl* entry) {
   if (!entry->screenshot().get())
     return false;
 
   entry->SetScreenshotPNGData(NULL);
   return true;
 }
@@ skipping 57 matching lines @@
         owner_->GetEntryAtIndex(forward));
     if (ClearScreenshot(entry))
       --screenshot_count;
     ++forward;
   }
   CHECK_GE(screenshot_count, 0);
   CHECK_LE(screenshot_count, kMaxScreenshots);
 }
 
 }  // namespace content