Android: Fix potential null-ptr deref

BrowserGpuChannelHostFactory::GetGpuChannel() can
return NULL. In particular it already checks
IsLost() and returns NULL if that is the case.

BUG=445945

Review URL: https://codereview.chromium.org/867093004

Cr-Commit-Position: refs/heads/master@{#314683}

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -158,8 +158,7 @@ GLHelperHolder::CreateContext3D() {
   scoped_refptr<GpuChannelHost> gpu_channel_host(factory->GetGpuChannel());
   // GLHelper can only be used in asynchronous APIs for postprocessing after
   // Browser Compositor operations (i.e. readback).
-  DCHECK(gpu_channel_host.get()) << "Illegal access to GPU channel at startup";
-  if (gpu_channel_host->IsLost()) {
+  if (!gpu_channel_host.get()) {
     // The Browser Compositor is in charge of reestablishing the channel.
     return scoped_ptr<WebGraphicsContext3DCommandBufferImpl>();
   }