Allow WebExternalTextureLayerClient to work with mailboxes.

cc/layers/texture_layer_unittest.cc

Index: cc/layers/texture_layer_unittest.cc
diff --git a/cc/layers/texture_layer_unittest.cc b/cc/layers/texture_layer_unittest.cc
index 450c3a12948924df77783eb4e07138a00e4723c4..c6a45499c88116f16e44442fa319f27cfe55aad8 100644
--- a/cc/layers/texture_layer_unittest.cc
+++ b/cc/layers/texture_layer_unittest.cc
@@ -234,7 +234,7 @@ class TextureLayerWithMailboxTest : public TextureLayerTest {
 };
 
 TEST_F(TextureLayerWithMailboxTest, ReplaceMailboxOnMainThreadBeforeCommit) {
-  scoped_refptr<TextureLayer> test_layer = TextureLayer::CreateForMailbox();
+  scoped_refptr<TextureLayer> test_layer = TextureLayer::CreateForMailbox(NULL);
   ASSERT_TRUE(test_layer);
 
   EXPECT_CALL(*layer_tree_host_, AcquireLayerTextures()).Times(0);
@@ -302,7 +302,7 @@ class TextureLayerImplWithMailboxThreadedCallback : public LayerTreeTest {
     root_->SetAnchorPoint(gfx::PointF());
     root_->SetBounds(bounds);
 
-    layer_ = TextureLayer::CreateForMailbox();
+    layer_ = TextureLayer::CreateForMailbox(NULL);
     layer_->SetIsDrawable(true);
     layer_->SetAnchorPoint(gfx::PointF());
     layer_->SetBounds(bounds);
@@ -521,6 +521,10 @@ class TextureLayerClientTest
     return context_;
   }
 
+  virtual bool PrepareTextureMailbox(cc::TextureMailbox* mailbox) OVERRIDE {
+    return false;
+  }
+
   virtual void SetupTree() OVERRIDE {
     scoped_refptr<Layer> root = Layer::Create();
     root->SetBounds(gfx::Size(10, 10));