Prevent browser thumbnailer from trying to read from frontbuffer (surface texture) when none exists.

chrome/browser/tab_contents/thumbnail_generator_unittest.cc

 // Copyright (c) 2012 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 "base/basictypes.h"
 #include "base/stringprintf.h"
 #include "chrome/browser/history/top_sites.h"
 #include "chrome/browser/tab_contents/thumbnail_generator.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/test/base/testing_profile.h"
@@ skipping 173 matching lines @@
   const GURL kBadURL("chrome://newtab");
 
   // Set up the profile.
   TestingProfile profile;
 
   // Set up the top sites service.
   ScopedTempDir temp_dir;
   ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
   scoped_refptr<MockTopSites> top_sites(new MockTopSites(&profile));
 
+  // Should be false when we don't have a surface
+  EXPECT_FALSE(ThumbnailGenerator::ShouldUpdateThumbnail(
+      &profile, top_sites.get(), kBadURL, false));
+
   // Should be false because it's a bad URL.
   EXPECT_FALSE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kBadURL));
+      &profile, top_sites.get(), kBadURL, true));
 
   // Should be true, as it's a good URL.
   EXPECT_TRUE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kGoodURL));
+      &profile, top_sites.get(), kGoodURL, true));
 
   // Should be false, if it's in the incognito mode.
   profile.set_incognito(true);
   EXPECT_FALSE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kGoodURL));
+      &profile, top_sites.get(), kGoodURL, true));
 
   // Should be true again, once turning off the incognito mode.
   profile.set_incognito(false);
   EXPECT_TRUE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kGoodURL));
+      &profile, top_sites.get(), kGoodURL, true));
 
   // Add a known URL. This makes the top sites data full.
   ThumbnailScore bad_score;
   bad_score.time_at_snapshot = base::Time::UnixEpoch();  // Ancient time stamp.
   top_sites->AddKnownURL(kGoodURL, bad_score);
   ASSERT_TRUE(top_sites->IsFull());
 
   // Should be false, as the top sites data is full, and the new URL is
   // not known.
   const GURL kAnotherGoodURL("http://www.youtube.com/");
   EXPECT_FALSE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kAnotherGoodURL));
+      &profile, top_sites.get(), kAnotherGoodURL, true));
 
   // Should be true, as the existing thumbnail is bad (i.e need a better one).
   EXPECT_TRUE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kGoodURL));
+      &profile, top_sites.get(), kGoodURL, true));
 
   // Replace the thumbnail score with a really good one.
   ThumbnailScore good_score;
   good_score.time_at_snapshot = base::Time::Now();  // Very new.
   good_score.at_top = true;
   good_score.good_clipping = true;
   good_score.boring_score = 0.0;
   good_score.load_completed = true;
   top_sites->AddKnownURL(kGoodURL, good_score);
 
   // Should be false, as the existing thumbnail is good enough (i.e. don't
   // need to replace the existing thumbnail which is new and good).
   EXPECT_FALSE(ThumbnailGenerator::ShouldUpdateThumbnail(
-      &profile, top_sites.get(), kGoodURL));
+      &profile, top_sites.get(), kGoodURL, true));
 }