Allow switching to SwiftShader when GPU is blacklisted

content/browser/gpu/gpu_process_host.h

Index: content/browser/gpu/gpu_process_host.h
diff --git a/content/browser/gpu/gpu_process_host.h b/content/browser/gpu/gpu_process_host.h
index 9f2b5206ec3aa8010d1f3e063596c2649ed380de..f4f226a376fd3d686bce341f693bfcf7ca144996 100644
--- a/content/browser/gpu/gpu_process_host.h
+++ b/content/browser/gpu/gpu_process_host.h
@@ -80,6 +80,9 @@ class GpuProcessHost : public BrowserChildProcessHost,
       const GPUCreateCommandBufferConfig& init_params,
       CreateCommandBufferCallback* callback);
 
+  // Whether this GPU process is set up to use software rendering.
+  bool software_rendering();
+
  private:
   GpuProcessHost(int host_id);
   virtual ~GpuProcessHost();
@@ -149,6 +152,8 @@ class GpuProcessHost : public BrowserChildProcessHost,
   // of a separate GPU process.
   bool in_process_;
 
+  bool software_rendering_;
+
   scoped_ptr<GpuMainThread> in_process_gpu_thread_;
 
   // Master switch for enabling/disabling GPU acceleration for the current