[Large Icon Service] Move icon resizing into worker thread.

components/favicon/core/large_icon_service_unittest.cc

Index: components/favicon/core/large_icon_service_unittest.cc
diff --git a/components/favicon/core/large_icon_service_unittest.cc b/components/favicon/core/large_icon_service_unittest.cc
index 48422ab55a39552a545d4d087af8528a9001bcfd..df7fcbd030b4209e31ebc4e79d146545ae084317 100644
--- a/components/favicon/core/large_icon_service_unittest.cc
+++ b/components/favicon/core/large_icon_service_unittest.cc
@@ -82,9 +82,9 @@ class MockFaviconService : public FaviconService {
   }
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(MockFaviconService);
-
   std::deque<favicon_base::FaviconRawBitmapResult> mock_result_queue_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockFaviconService);
 };
 
 // This class provides access to LargeIconService internals.
@@ -96,6 +96,11 @@ class TestLargeIconService : public LargeIconService {
   ~TestLargeIconService() override {
   }
 
+  // Using the current thread's task runner for testing.
+  scoped_refptr<base::TaskRunner> GetBackgroundTaskRunner() override {
+    return base::MessageLoop::current()->task_runner();
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(TestLargeIconService);
 };
@@ -152,7 +157,6 @@ class LargeIconServiceTest : public testing::Test {
 };
 
 TEST_F(LargeIconServiceTest, SameSize) {
-
   mock_favicon_service_->InjectResult(CreateTestBitmap(24, 24, kTestColor));
   expected_bitmap_ = CreateTestBitmap(24, 24, kTestColor);
   large_icon_service_->GetLargeIconOrFallbackStyle(