Enable creation of offscreen contexts which own their backing surface.

gpu/ipc/service/gpu_command_buffer_stub.cc

Index: gpu/ipc/service/gpu_command_buffer_stub.cc
diff --git a/gpu/ipc/service/gpu_command_buffer_stub.cc b/gpu/ipc/service/gpu_command_buffer_stub.cc
index b6396195afabdcb5ec8d6c46d8e5f253f00e02fe..48c2cc8a7b7d0e0674fad4cd1376cfae08043fea 100644
--- a/gpu/ipc/service/gpu_command_buffer_stub.cc
+++ b/gpu/ipc/service/gpu_command_buffer_stub.cc
@@ -566,7 +566,29 @@ bool GpuCommandBufferStub::Initialize(
   decoder_->set_engine(executor_.get());
 
   if (offscreen) {
-    surface_ = default_surface;
+    if (init_params.attribs.own_offscreen_surface) {
+      use_virtualized_gl_context_ = false;
+      int depth = init_params.attribs.depth_size;
+      if (depth > 0) {
+        if (depth == 24 && surface_format == gl::GLSurface::SURFACE_ARGB8888) {
+          surface_format = gl::GLSurface::SURFACE_ARGB8888_DEPTH24;
+        } else if (depth == 24 &&
+                   surface_format == gl::GLSurface::SURFACE_RGB565) {
+          surface_format = gl::GLSurface::SURFACE_RGB565_DEPTH24;
+        } else {
+          DLOG(ERROR) << "Failed to create surface, can't add depth_size="
+                      << depth << " to base format " << surface_format;

[piman, 2016/11/16 00:44:02]

Should we fail initialization here, then? I.e. return false.

[dcheng, 2016/11/17 01:17:00]

+1, this is coming from the renderer right? We need to gracefully handle invalid
or otherwise impossible combinations here.

[klausw, 2017/01/05 02:17:43]

Please see the new logic, I think it's much cleaner now that it's
using a GLSurfaceFormat structure with Get/SetDepthBits() and related
accessors.

+        }
+      }
+      surface_ = gl::init::CreateUninitializedOffscreenGLSurface(gfx::Size());
+      if (!surface_ || !surface_->Initialize(surface_format)) {
+        surface_ = nullptr;
+        DLOG(ERROR) << "Failed to create surface.";
+        return false;
+      }
+    } else {
+      surface_ = default_surface;
+    }
   } else {
     surface_ = ImageTransportSurface::CreateNativeSurface(
         AsWeakPtr(), surface_handle_, surface_format);