Revert of Pass initial size and GPU preference via context attributes

blimp/client/feature/compositor/blimp_context_provider.cc

Index: blimp/client/feature/compositor/blimp_context_provider.cc
diff --git a/blimp/client/feature/compositor/blimp_context_provider.cc b/blimp/client/feature/compositor/blimp_context_provider.cc
index a87aeef522f8c80efd76c2e676a0aa5ba3b52c8b..a4699fee8df78e35740827ae02aaf4fde7c0878f 100644
--- a/blimp/client/feature/compositor/blimp_context_provider.cc
+++ b/blimp/client/feature/compositor/blimp_context_provider.cc
@@ -43,9 +43,9 @@
 
   context_.reset(gpu::GLInProcessContext::Create(
       nullptr /* service */, nullptr /* surface */, false /* is_offscreen */,
-      widget, nullptr /* share_context */, attribs_for_gles2,
-      gpu::SharedMemoryLimits(), gpu_memory_buffer_manager,
-      nullptr /* memory_limits */));
+      widget, gfx::Size(1, 1), nullptr /* share_context */, attribs_for_gles2,
+      gl::PreferDiscreteGpu, gpu::SharedMemoryLimits(),
+      gpu_memory_buffer_manager, nullptr /* memory_limits */));
   context_->GetImplementation()->SetLostContextCallback(
       base::Bind(&BlimpContextProvider::OnLostContext, base::Unretained(this)));
 }