Move purging from OnMemoryState to OnPurgeMemory() in cc/

cc/tiles/gpu_image_decode_cache_unittest.cc

 // Copyright 2016 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 "cc/tiles/gpu_image_decode_cache.h"
 
 #include "cc/playback/draw_image.h"
 #include "cc/test/test_context_provider.h"
 #include "cc/test/test_tile_task_runner.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 1318 matching lines @@
   DCHECK_GT(cache.GetBytesUsedForTesting(), 0u);
   DCHECK_EQ(cache.GetNumCacheEntriesForTesting(), 1u);
 
   // Set us to the not visible state (prerequisite for SUSPENDED).
   cache.SetShouldAggressivelyFreeResources(true);
 
   // Image should be cached, but not using memory budget.
   DCHECK_EQ(cache.GetBytesUsedForTesting(), 0u);
   DCHECK_EQ(cache.GetNumCacheEntriesForTesting(), 1u);
 
-  // Set us to the SUSPENDED state.
+  // Set us to the SUSPENDED state with purging.
+  cache.OnPurgeMemory();
   cache.OnMemoryStateChange(base::MemoryState::SUSPENDED);
 
   // Nothing should be cached.
   DCHECK_EQ(cache.GetBytesUsedForTesting(), 0u);
   DCHECK_EQ(cache.GetNumCacheEntriesForTesting(), 0u);
 
   // Attempts to get a task for the image should fail, as we have no space (at
   // raster only).
   need_unref = cache.GetTaskForImageAndRef(
       draw_image, ImageDecodeCache::TracingInfo(), &task);
@@ skipping 36 matching lines @@
   // Run the decode task.
   TestTileTaskRunner::ProcessTask(task.get());
 
   // The image should remain in the cache till we unref it.
   EXPECT_TRUE(cache.IsInInUseCacheForTesting(draw_image));
   cache.UnrefImage(draw_image);
 }
 
 }  // namespace
 }  // namespace cc