Introduce CompositorDependencies for RenderWidgetCompositor.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 537694ea95cf7573da4334b78af6a6b0059e8990..e6888f9a627e209a25df11d876965c8f4a116855 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -35,6 +35,7 @@
 #include "content/public/common/context_menu_params.h"
 #include "content/renderer/cursor_utils.h"
 #include "content/renderer/external_popup_menu.h"
+#include "content/renderer/gpu/compositor_dependencies_impl.h"
 #include "content/renderer/gpu/compositor_output_surface.h"
 #include "content/renderer/gpu/compositor_software_output_device.h"
 #include "content/renderer/gpu/delegated_compositor_output_surface.h"
@@ -153,11 +154,6 @@ ui::TextInputMode ConvertInputMode(const blink::WebString& input_mode) {
   return it->second;
 }
 
-bool IsThreadedCompositingEnabled() {
-  content::RenderThreadImpl* impl = content::RenderThreadImpl::current();
-  return impl && !!impl->compositor_message_loop_proxy().get();
-}
-
 // TODO(brianderson): Replace the hard-coded threshold with a fraction of
 // the BeginMainFrame interval.
 // 4166us will allow 1/4 of a 60Hz interval or 1/2 of a 120Hz interval to
@@ -963,7 +959,7 @@ scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
 
   uint32 output_surface_id = next_output_surface_id_++;
   if (command_line.HasSwitch(switches::kEnableDelegatedRenderer)) {
-    DCHECK(IsThreadedCompositingEnabled());
+    DCHECK(compositor_deps_->GetCompositorImplThreadTaskRunner());
     return scoped_ptr<cc::OutputSurface>(
         new DelegatedCompositorOutputSurface(routing_id(),
                                              output_surface_id,
@@ -987,8 +983,7 @@ scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
     // Composite-to-mailbox is currently used for layout tests in order to cause
     // them to draw inside in the renderer to do the readback there. This should
     // no longer be the case when crbug.com/311404 is fixed.
-    DCHECK(IsThreadedCompositingEnabled() ||
-           RenderThreadImpl::current()->layout_test_mode());
+    DCHECK(RenderThreadImpl::current()->layout_test_mode());
     cc::ResourceFormat format = cc::RGBA_8888;
     if (base::SysInfo::IsLowEndDevice())
       format = cc::RGB_565;
@@ -1293,8 +1288,16 @@ void RenderWidget::AutoResizeCompositor()  {
 void RenderWidget::initializeLayerTreeView() {
   DCHECK(!host_closing_);
 
-  compositor_ =
-      RenderWidgetCompositor::Create(this, IsThreadedCompositingEnabled());
+  RenderThreadImpl* render_thread = RenderThreadImpl::current();
+  // RenderThreadImpl can be null in tests, but is not null for tests that use
+  // a compositor. For future tests that end up wanting to use a compositor but
+  // have a null RenderThreadImpl, they should inject a custom
+  // CompositorDependencies instead of using the default implementation here.
+  DCHECK(render_thread);
+
+  compositor_deps_ =
+      make_scoped_ptr(new CompositorDependenciesImpl(render_thread));
+  compositor_ = RenderWidgetCompositor::Create(this, compositor_deps_.get());
   compositor_->setViewportSize(size_, physical_backing_size_);
   if (init_complete_)
     StartCompositor();
@@ -2152,6 +2155,10 @@ void RenderWidget::StartCompositor() {
   // at all.
   if (never_visible_)
     return;
+  // In tests without a RenderThreadImpl, don't set ready as this kicks
+  // off creating output surfaces that the test can't create.
+  if (!RenderThreadImpl::current())
+    return;
   compositor_->setSurfaceReady();
 }