Have a common implementation of cc::OutputSurface

cc/test/fake_output_surface.cc

Index: cc/test/fake_output_surface.cc
diff --git a/cc/test/fake_output_surface.cc b/cc/test/fake_output_surface.cc
index ebbe7832b167284c658db7e168433797148d81ba..0b9a6d3dd98d3fd65febf22d8343cfaf078bed9d 100644
--- a/cc/test/fake_output_surface.cc
+++ b/cc/test/fake_output_surface.cc
@@ -8,41 +8,27 @@ namespace cc {
 
 FakeOutputSurface::FakeOutputSurface(
     scoped_ptr<WebKit::WebGraphicsContext3D> context3d, bool has_parent)
-    : num_sent_frames_(0) {
-  context3d_ = context3d.Pass();
+    : OutputSurface(context3d.Pass()),
+      num_sent_frames_(0) {
   capabilities_.has_parent_compositor = has_parent;
 }
 
 FakeOutputSurface::FakeOutputSurface(
     scoped_ptr<SoftwareOutputDevice> software_device, bool has_parent)
-    : num_sent_frames_(0) {
-  software_device_ = software_device.Pass();
+    : OutputSurface(software_device.Pass()),
+      num_sent_frames_(0) {
   capabilities_.has_parent_compositor = has_parent;
 }
 
 FakeOutputSurface::~FakeOutputSurface() {}
 
-bool FakeOutputSurface::BindToClient(OutputSurfaceClient* client) {
-  if (!context3d_)
-    return true;
+bool FakeOutputSurface::BindToClient(
+    cc::OutputSurfaceClient* client) {
   DCHECK(client);
-  if (!context3d_->makeContextCurrent())
-    return false;
   client_ = client;
-  return true;
-}
-
-const struct OutputSurface::Capabilities& FakeOutputSurface::Capabilities()
-    const {
-  return capabilities_;
-}
-
-WebKit::WebGraphicsContext3D* FakeOutputSurface::Context3D() const {
-  return context3d_.get();
-}
-
-SoftwareOutputDevice* FakeOutputSurface::SoftwareDevice() const {
-  return software_device_.get();
+  if (!context3d_)
+    return true;
+  return context3d_->makeContextCurrent();
 }
 
 void FakeOutputSurface::SendFrameToParentCompositor(