Fix more uses of T* conversion operator from scoped_refptr<T> which is now removed

Fix more uses of T* conversion operator from scoped_refptr<T> which is now removed.

Please see https://codereview.chromium.org/510323002 for reference.

TEST=ozone_demo and content_shell under Ozone-GBM
BUG=none
NOTRY=true

Review URL: https://codereview.chromium.org/552133004

Cr-Commit-Position: refs/heads/master@{#294172}

ui/ozone/demo/ozone_demo.cc

@@ -86,14 +86,14 @@ class DemoWindow : public ui::PlatformWindowDelegate {
  private:
   bool InitializeGLSurface() {
     surface_ = gfx::GLSurface::CreateViewGLSurface(GetAcceleratedWidget());
-    if (!surface_) {
+    if (!surface_.get()) {
       LOG(ERROR) << "Failed to create GL surface";
       return false;
     }
 
     context_ = gfx::GLContext::CreateGLContext(
         NULL, surface_.get(), gfx::PreferIntegratedGpu);
-    if (!context_) {
+    if (!context_.get()) {
       LOG(ERROR) << "Failed to create GL context";
       surface_ = NULL;
       return false;

ui/ozone/platform/dri/gbm_surface.cc

@@ -135,9 +135,9 @@ bool GbmSurface::OnSwapBuffers() {
   gbm_bo* pending_buffer = gbm_surface_lock_front_buffer(native_surface_);
   scoped_refptr<GbmSurfaceBuffer> primary =
       GbmSurfaceBuffer::GetBuffer(pending_buffer);
-  if (!primary) {
+  if (!primary.get()) {
     primary = GbmSurfaceBuffer::CreateBuffer(dri_, pending_buffer);
-    if (!primary) {
+    if (!primary.get()) {
       LOG(ERROR) << "Failed to associate the buffer with the controller";
       return false;
     }

ui/ozone/platform/dri/gbm_surface_factory.cc

@@ -174,7 +174,7 @@ scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
     BufferFormat format) {
   scoped_refptr<GbmBuffer> buffer = GbmBuffer::CreateBuffer(
       drm_, device_, format, size, true);
-  if (!buffer)
+  if (!buffer.get())
     return NULL;
 
   return scoped_refptr<GbmPixmap>(new GbmPixmap(buffer));
@@ -196,7 +196,7 @@ bool GbmSurfaceFactory::ScheduleOverlayPlane(
     const gfx::Rect& display_bounds,
     const gfx::RectF& crop_rect) {
   scoped_refptr<GbmPixmap> pixmap = static_cast<GbmPixmap*>(buffer.get());
-  if (!pixmap) {
+  if (!pixmap.get()) {
     LOG(ERROR) << "ScheduleOverlayPlane passed NULL buffer.";
     return false;
   }