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

content/renderer/render_widget.cc

 // Copyright (c) 2012 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 "content/renderer/render_widget.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 617 matching lines @@
 }
 
 GURL RenderWidget::GetURLForGraphicsContext3D() {
   return GURL();
 }
 
 bool RenderWidget::ForceCompositingModeEnabled() {
   return false;
 }
 
-scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface() {
+scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
 #if defined(OS_ANDROID)
    if (SynchronousCompositorFactory* factory =
        SynchronousCompositorFactory::GetInstance()) {
     return factory->CreateOutputSurface(routing_id());
   }
 #endif
 
   uint32 output_surface_id = next_output_surface_id_++;
 
-  if (command_line.HasSwitch(switches::kEnableSoftwareCompositingGLAdapter)) {
-      return scoped_ptr<cc::OutputSurface>(
-          new CompositorOutputSurface(routing_id(), output_surface_id, NULL,
-              new CompositorSoftwareOutputDevice(), true));
-  }
-
   // Explicitly disable antialiasing for the compositor. As of the time of
   // this writing, the only platform that supported antialiasing for the
   // compositor was Mac OS X, because the on-screen OpenGL context creation
   // code paths on Windows and Linux didn't yet have multisampling support.
   // Mac OS X essentially always behaves as though it's rendering offscreen.
   // Multisampling has a heavy cost especially on devices with relatively low
   // fill rate like most notebooks, and the Mac implementation would need to
   // be optimized to resolve directly into the IOSurface shared between the
   // GPU and browser processes. For these reasons and to avoid platform
   // disparities we explicitly disable antialiasing.
   WebKit::WebGraphicsContext3D::Attributes attributes;
   attributes.antialias = false;
   attributes.shareResources = true;
   attributes.noAutomaticFlushes = true;
   attributes.depth = false;
   attributes.stencil = false;
   if (command_line.HasSwitch(cc::switches::kForceDirectLayerDrawing))
     attributes.stencil = true;
-  WebGraphicsContext3DCommandBufferImpl* context =
-      CreateGraphicsContext3D(attributes);
-  if (!context)
-    return scoped_ptr<cc::OutputSurface>();
+  WebGraphicsContext3DCommandBufferImpl* context = NULL;
+  if (!fallback)
+    context = CreateGraphicsContext3D(attributes);
+
+  if (!context) {
+    if (!command_line.HasSwitch(switches::kEnableSoftwareCompositing))
+      return scoped_ptr<cc::OutputSurface>();
+    return scoped_ptr<cc::OutputSurface>(
+        new CompositorOutputSurface(routing_id(),
+                                    output_surface_id,
+                                    NULL,
+                                    new CompositorSoftwareOutputDevice(),
+                                    true));
+  }
 
   if (command_line.HasSwitch(switches::kEnableDelegatedRenderer) &&
       !command_line.HasSwitch(switches::kDisableDelegatedRenderer)) {
     DCHECK(is_threaded_compositing_enabled_);
     return scoped_ptr<cc::OutputSurface>(
         new DelegatedCompositorOutputSurface(routing_id(), output_surface_id,
                                              context, NULL));
   }
   if (command_line.HasSwitch(cc::switches::kCompositeToMailbox)) {
     DCHECK(is_threaded_compositing_enabled_);
@@ skipping 1785 matching lines @@
 }
 
 bool RenderWidget::HasTouchEventHandlersAt(const gfx::Point& point) const {
   return true;
 }
 
 WebGraphicsContext3DCommandBufferImpl* RenderWidget::CreateGraphicsContext3D(
     const WebKit::WebGraphicsContext3D::Attributes& attributes) {
   if (!webwidget_)
     return NULL;
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableGpuCompositing))
+    return NULL;
   scoped_ptr<WebGraphicsContext3DCommandBufferImpl> context(
       new WebGraphicsContext3DCommandBufferImpl(
           surface_id(),
           GetURLForGraphicsContext3D(),
           RenderThreadImpl::current(),
           weak_ptr_factory_.GetWeakPtr()));
 
   if (!context->InitializeWithDefaultBufferSizes(
           attributes,
           false /* bind generates resources */,
           CAUSE_FOR_GPU_LAUNCH_WEBGRAPHICSCONTEXT3DCOMMANDBUFFERIMPL_INITIALIZE))
     return NULL;
   return context.release();
 }
 
 }  // namespace content