content: Add command line flag for native GPU memory buffers.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index e49dcfec0392399e8d24aaba917436b782615605..2d6d5b7b681b6c4d43be796203b02b6f17510a6d 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -151,22 +151,6 @@ size_t GetMaxTransferBufferUsageBytes(
                   max_transfer_buffer_usage_bytes);
 }
 
-unsigned GetMapImageTextureTarget(
-    const ContextProvider::Capabilities& context_capabilities) {
-// TODO(reveman): This should be a setting passed to the compositor instead
-// of hard-coded here. The target that need to be used depends on our choice
-// of GpuMemoryBuffer type. Note: SURFACE_TEXTURE needs EXTERNAL_OES,
-// IO_SURFACE needs RECTANGLE_ARB. crbug.com/431059
-#if defined(OS_ANDROID)
-  if (context_capabilities.gpu.egl_image_external)
-    return GL_TEXTURE_EXTERNAL_OES;
-#endif
-  if (context_capabilities.gpu.texture_rectangle)
-    return GL_TEXTURE_RECTANGLE_ARB;
-
-  return GL_TEXTURE_2D;
-}
-
 size_t GetMaxStagingResourceCount() {
   // Upper bound for number of staging resource to allow.
   return 32;
@@ -2008,6 +1992,17 @@ void LayerTreeHostImpl::CreateResourceAndRasterWorkerPool(
   bool should_use_zero_copy_rasterizer =
       settings_.use_zero_copy || IsSynchronousSingleThreaded();
 
+  unsigned image_target = GL_TEXTURE_2D;
+#if defined(OS_MACOSX)
+  // GL_TEXTURE_RECTANGLE_ARB target is required by IOSurface backed images.
+  DCHECK(context_provider->ContextCapabilities().gpu.texture_rectangle);

[piman, 2014/11/25 18:12:21]

Would it make sense to ask the GpuMemoryBufferImpl which texture target it
should use?

[reveman, 2014/11/25 19:36:11]

Maybe. I'm not sure I want the concept of GL texture targets at the
gfx::GpuMemoryBuffer level. We could add something to the CHROMIUM_image API for
this but I'm not sure exactly what that would look like. And if we make it a
buffer specific setting in cc (where we're not currently assuming that all
buffers are of the same type) it breaks our current resource pool usage where we
assume that all buffers use the same target.

Another option is to introduce a new chromium only texture target that must be
used with CHROMIUM_image, call it EXTERNAL_CHROMIUM. The use of this target
would be limited much in the same way as EXTERNAL_OES. The GPU service would
then automatically use the correct GL target based on buffer type. I think this
would be cleanest solution but hard to implement as texture coordinates can't be
normalized in the RECTANGLE_ARB case...

I think it's easiest to handle this using ifdefs and a setting for now.

+  image_target = GL_TEXTURE_RECTANGLE_ARB;
+#endif
+  if (settings_.use_image_external) {
+    DCHECK(context_provider->ContextCapabilities().gpu.egl_image_external);
+    image_target = GL_TEXTURE_EXTERNAL_OES;
+  }
+
   if (!context_provider) {
     *resource_pool =
         ResourcePool::Create(resource_provider_.get(),
@@ -2030,10 +2025,9 @@ void LayerTreeHostImpl::CreateResourceAndRasterWorkerPool(
                                     resource_provider_.get(),
                                     settings_.use_distance_field_text);
   } else if (should_use_zero_copy_rasterizer && CanUseZeroCopyRasterizer()) {
-    *resource_pool = ResourcePool::Create(
-        resource_provider_.get(),
-        GetMapImageTextureTarget(context_provider->ContextCapabilities()),
-        resource_provider_->best_texture_format());
+    *resource_pool =
+        ResourcePool::Create(resource_provider_.get(), image_target,
+                             resource_provider_->best_texture_format());
 
     TaskGraphRunner* task_graph_runner;
     if (IsSynchronousSingleThreaded()) {
@@ -2048,10 +2042,9 @@ void LayerTreeHostImpl::CreateResourceAndRasterWorkerPool(
         task_runner, task_graph_runner, resource_provider_.get());
   } else if (settings_.use_one_copy && CanUseOneCopyRasterizer()) {
     // We need to create a staging resource pool when using copy rasterizer.
-    *staging_resource_pool = ResourcePool::Create(
-        resource_provider_.get(),
-        GetMapImageTextureTarget(context_provider->ContextCapabilities()),
-        resource_provider_->best_texture_format());
+    *staging_resource_pool =
+        ResourcePool::Create(resource_provider_.get(), image_target,
+                             resource_provider_->best_texture_format());
     *resource_pool =
         ResourcePool::Create(resource_provider_.get(),
                              GL_TEXTURE_2D,