Revert of Pass initial size and GPU preference via context attributes

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 4b6ea5b8f326ef04ec45210e6b0822f5a042d042..28ccd4eec19289959e3d5f2647e55593205661a4 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -585,6 +585,7 @@
   bool Initialize(const scoped_refptr<gl::GLSurface>& surface,
                   const scoped_refptr<gl::GLContext>& context,
                   bool offscreen,
+                  const gfx::Size& offscreen_size,
                   const DisallowedFeatures& disallowed_features,
                   const ContextCreationAttribHelper& attrib_helper) override;
   void Destroy(bool have_context) override;
@@ -2911,11 +2912,13 @@
     const scoped_refptr<gl::GLSurface>& surface,
     const scoped_refptr<gl::GLContext>& context,
     bool offscreen,
+    const gfx::Size& offscreen_size,
     const DisallowedFeatures& disallowed_features,
     const ContextCreationAttribHelper& attrib_helper) {
   TRACE_EVENT0("gpu", "GLES2DecoderImpl::Initialize");
   DCHECK(context->IsCurrent(surface.get()));
   DCHECK(!context_.get());
+  DCHECK(!offscreen || !offscreen_size.IsEmpty());
 
   surfaceless_ = surface->IsSurfaceless() && !offscreen;
 
@@ -3211,26 +3214,16 @@
     offscreen_saved_color_texture_.reset(new BackTexture(this));
     offscreen_saved_color_texture_->Create();
 
-    gfx::Size initial_size = attrib_helper.offscreen_framebuffer_size;
-    if (initial_size.IsEmpty()) {
-      // If we're an offscreen surface with zero width and/or height, set to a
-      // non-zero size so that we have a complete framebuffer for operations
-      // like glClear.
-      // TODO(piman): allow empty framebuffers, similar to
-      // EGL_KHR_surfaceless_context / GL_OES_surfaceless_context.
-      initial_size = gfx::Size(1, 1);
-    }
-
     // Allocate the render buffers at their initial size and check the status
     // of the frame buffers is okay.
-    if (!ResizeOffscreenFrameBuffer(initial_size)) {
+    if (!ResizeOffscreenFrameBuffer(offscreen_size)) {
       LOG(ERROR) << "Could not allocate offscreen buffer storage.";
       Destroy(true);
       return false;
     }
 
-    state_.viewport_width = initial_size.width();
-    state_.viewport_height = initial_size.height();
+    state_.viewport_width = offscreen_size.width();
+    state_.viewport_height = offscreen_size.height();
 
     // Allocate the offscreen saved color texture.
     DCHECK(offscreen_saved_color_format_);