Remove the ENABLE_GPU #define and enable_gpu gyp variable

content/common/gpu/gpu_channel.cc

Index: content/common/gpu/gpu_channel.cc
diff --git a/content/common/gpu/gpu_channel.cc b/content/common/gpu/gpu_channel.cc
index 1876250144df82efd1e425a62708c1c485c85f28..ddcd34ef20fae8cf6230fb854afb0e75ab3d37a1 100644
--- a/content/common/gpu/gpu_channel.cc
+++ b/content/common/gpu/gpu_channel.cc
@@ -617,8 +617,6 @@ void GpuChannel::CreateViewCommandBuffer(
 
   *route_id = MSG_ROUTING_NONE;
 
-#if defined(ENABLE_GPU)
-
   GpuCommandBufferStub* share_group = stubs_.Lookup(init_params.share_group_id);
 
   // Virtualize compositor contexts on OS X to prevent performance regressions
@@ -650,7 +648,6 @@ void GpuChannel::CreateViewCommandBuffer(
     stub->SetPreemptByFlag(preempted_flag_);
   router_.AddRoute(*route_id, stub.get());
   stubs_.AddWithID(stub.release(), *route_id);
-#endif  // ENABLE_GPU
 }
 
 GpuCommandBufferStub* GpuChannel::LookupCommandBuffer(int32 route_id) {