Add missing (and remove superfluous) 'explicit' from constructors.

cc/layer_unittest.cc

 // Copyright 2011 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/layer.h"
 
 #include "cc/keyframed_animation_curve.h"
 #include "cc/layer_impl.h"
 #include "cc/layer_painter.h"
 #include "cc/layer_tree_host.h"
@@ skipping 600 matching lines @@
 public:
     static scoped_ptr<FakeLayerImplTreeHost> create()
     {
         scoped_ptr<FakeLayerImplTreeHost> host(new FakeLayerImplTreeHost(LayerTreeSettings()));
         // The initialize call will fail, since our client doesn't provide a valid GraphicsContext3D, but it doesn't matter in the tests that use this fake so ignore the return value.
         host->initialize(scoped_ptr<Thread>(NULL));
         return host.Pass();
     }
 
 private:
-    FakeLayerImplTreeHost(const LayerTreeSettings& settings)
+    explicit FakeLayerImplTreeHost(const LayerTreeSettings& settings)
         : LayerTreeHost(&m_client, settings)
     {
     }
 
     FakeLayerImplTreeHostClient m_client;
 };
 
 void assertLayerTreeHostMatchesForSubtree(Layer* layer, LayerTreeHost* host)
 {
     EXPECT_EQ(host, layer->layerTreeHost());
@@ skipping 222 matching lines @@
     scoped_refptr<MockLayer> layer(new MockLayer);
     EXPECT_FALSE(layer->needsDisplay());
     layer->setBounds(gfx::Size(0, 10));
     EXPECT_FALSE(layer->needsDisplay());
     layer->setBounds(gfx::Size(10, 10));
     EXPECT_TRUE(layer->needsDisplay());
 }
 
 }  // namespace
 }  // namespace cc