Add a flag to allow renderer to use software compositor when GL compositor doesn't work.

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 f4482ac0d5ae103c8ddfbed9e4417557a7abff5f..d7618a78594d0ce570b421a5d2960c6e5333e076 100644
--- a/cc/layers/texture_layer_unittest.cc
+++ b/cc/layers/texture_layer_unittest.cc
@@ -765,7 +765,8 @@ class TextureLayerClientTest
         expected_used_textures_on_draw_(0),
         expected_used_textures_on_commit_(0) {}
 
-  virtual scoped_ptr<OutputSurface> CreateOutputSurface() OVERRIDE {
+  virtual scoped_ptr<OutputSurface> CreateOutputSurface(bool fallback)
+      OVERRIDE {
     scoped_ptr<TestWebGraphicsContext3D> context(
         TestWebGraphicsContext3D::Create());
     context_ = context.get();
@@ -879,7 +880,8 @@ class TextureLayerLostContextTest
       : texture_(0),
         draw_count_(0) {}
 
-  virtual scoped_ptr<OutputSurface> CreateOutputSurface() OVERRIDE {
+  virtual scoped_ptr<OutputSurface> CreateOutputSurface(bool fallback)
+      OVERRIDE {
     texture_context_ = TestWebGraphicsContext3D::Create();
     texture_ = texture_context_->createTexture();
     return CreateFakeOutputSurface();