content: Add overdraw feedback support for X11 ChromeOS builds.

content/browser/compositor/gpu_process_transport_factory.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/compositor/gpu_process_transport_factory.h"
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 93 matching lines @@
 const int kNumRetriesBeforeSoftwareFallback = 4;
 
 bool IsUsingMus() {
   return service_manager::ServiceManagerIsRemote();
 }
 
 scoped_refptr<ui::ContextProviderCommandBuffer> CreateContextCommon(
     scoped_refptr<gpu::GpuChannelHost> gpu_channel_host,
     gpu::SurfaceHandle surface_handle,
     bool need_alpha_channel,
+    bool need_stencil_bits,
     bool support_locking,
     ui::ContextProviderCommandBuffer* shared_context_provider,
     ui::command_buffer_metrics::ContextType type) {
   DCHECK(
       content::GpuDataManagerImpl::GetInstance()->CanUseGpuBrowserCompositor());
   DCHECK(gpu_channel_host);
 
   // This is called from a few places to create different contexts:
   // - The shared main thread context (offscreen).
   // - The compositor context, which is used by the browser compositor
   //   (offscreen) for synchronization mostly, and by the display compositor
   //   (onscreen, except for with mus) for actual GL drawing.
   // - The compositor worker context (offscreen) used for GPU raster.
   // So ask for capabilities needed by any of these cases (we can optimize by
   // branching on |surface_handle| being null if these needs diverge).
   //
   // The default framebuffer for an offscreen context is not used, so it does
   // not need alpha, stencil, depth, antialiasing. The display compositor does
-  // not use these things either, so we can request nothing here.
-  // The display compositor does not use these things either (except for alpha
-  // when using mus for non-opaque ui that overlaps the system's window
-  // borders), so we can request only that when needed.
+  // not use these things either (except for alpha when using mus for
+  // non-opaque ui that overlaps the system's window borders or stencil bits
+  // for overdraw feedback), so we can request only that when needed.
   gpu::gles2::ContextCreationAttribHelper attributes;
   attributes.alpha_size = need_alpha_channel ? 8 : -1;
   attributes.depth_size = 0;
-  attributes.stencil_size = 0;
+  attributes.stencil_size = need_stencil_bits ? 8 : 0;

[jbauman, 2017/01/19 01:53:59]

On linux I don't think this actually affects whether or not the window gets a
stencil. We always try to choose a visual for every window that doesn't have a
stencil if there is a visual that doesn't have a stencil.

[reveman, 2017/01/19 04:15:08]

It doesn't but it effects if we allow some stencil operations or not. See:

https://cs.chromium.org/chromium/src/gpu/command_buffer/service/gles2_cmd_dec...
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/gles2_cmd_dec...

   attributes.samples = 0;
   attributes.sample_buffers = 0;
   attributes.bind_generates_resource = false;
   attributes.lose_context_when_out_of_memory = true;
   attributes.buffer_preserved = false;
 
   constexpr bool automatic_flushes = false;
 
   GURL url("chrome://gpu/GpuProcessTransportFactory::CreateContextCommon");
   return make_scoped_refptr(new ui::ContextProviderCommandBuffer(
@@ skipping 190 matching lines @@
   if (num_attempts > kNumRetriesBeforeSoftwareFallback) {
     bool fatal = IsUsingMus();
 #if defined(OS_CHROMEOS)
     fatal = true;
 #endif
     LOG_IF(FATAL, fatal) << "Unable to create a UI graphics context, and "
                          << "cannot use software compositing on ChromeOS.";
     create_gpu_output_surface = false;
   }
 
+  bool support_stencil = false;
+#if defined(OS_CHROMEOS)
+  // ChromeOS uses surfaceless when running on a real device and stencil
+  // buffers can then be added dynamically so supporting them does not have an
+  // impact on normal usage. If we are not running on a real ChromeOS device
+  // but instead on a workstation for development, then stencil support is
+  // useful as it allows the overdraw feedback debugging feature to be used.
+  support_stencil = true;
+#endif
+
 #if defined(OS_WIN)
   gfx::RenderingWindowManager::GetInstance()->RegisterParent(
       compositor->widget());
 #endif
 
   scoped_refptr<cc::VulkanInProcessContextProvider> vulkan_context_provider =
       SharedVulkanContextProvider();
   scoped_refptr<ui::ContextProviderCommandBuffer> context_provider;
   if (create_gpu_output_surface && !vulkan_context_provider) {
     // Try to reuse existing worker context provider.
@@ skipping 15 matching lines @@
       gpu_channel_host = std::move(established_channel_host);
 
     if (!gpu_channel_host) {
       shared_worker_context_provider_ = nullptr;
     } else {
       if (!shared_worker_context_provider_) {
         bool need_alpha_channel = false;
         const bool support_locking = true;
         shared_worker_context_provider_ = CreateContextCommon(
             gpu_channel_host, gpu::kNullSurfaceHandle, need_alpha_channel,
-            support_locking, nullptr,
+            false /* support_stencil */, support_locking, nullptr,
             ui::command_buffer_metrics::BROWSER_WORKER_CONTEXT);
         // TODO(vadimt): Remove ScopedTracker below once crbug.com/125248 is
         // fixed. Tracking time in BindToCurrentThread.
         tracked_objects::ScopedTracker tracking_profile(
             FROM_HERE_WITH_EXPLICIT_FUNCTION(
                 "125248"
                 " GpuProcessTransportFactory::EstablishedGpuChannel"
                 "::Worker"));
         if (!shared_worker_context_provider_->BindToCurrentThread())
           shared_worker_context_provider_ = nullptr;
       }
 
       // The |context_provider| is used for both the browser compositor and the
       // display compositor. It shares resources with the worker context, so if
       // we failed to make a worker context, just start over and try again.
       if (shared_worker_context_provider_) {
         // For mus, we create an offscreen context for a mus window, and we will
         // use CommandBufferProxyImpl::TakeFrontBuffer() to take the context's
         // front buffer into a mailbox, insert a sync token, and send the
         // mailbox+sync to the ui service process.
         gpu::SurfaceHandle surface_handle =
             IsUsingMus() ? gpu::kNullSurfaceHandle : data->surface_handle;
         bool need_alpha_channel = IsUsingMus();
         bool support_locking = false;
         context_provider = CreateContextCommon(
             std::move(gpu_channel_host), surface_handle, need_alpha_channel,
-            support_locking, shared_worker_context_provider_.get(),
+            support_stencil, support_locking,
+            shared_worker_context_provider_.get(),
             ui::command_buffer_metrics::DISPLAY_COMPOSITOR_ONSCREEN_CONTEXT);
         // TODO(vadimt): Remove ScopedTracker below once crbug.com/125248 is
         // fixed. Tracking time in BindToCurrentThread.
         tracked_objects::ScopedTracker tracking_profile(
             FROM_HERE_WITH_EXPLICIT_FUNCTION(
                 "125248"
                 " GpuProcessTransportFactory::EstablishedGpuChannel"
                 "::Compositor"));
 #if defined(OS_MACOSX)
         // On Mac, GpuCommandBufferMsg_SwapBuffersCompleted must be handled in
@@ skipping 90 matching lines @@
             validator;
         const bool use_mus = IsUsingMus();
 #if !defined(OS_MACOSX)
         // Overlays are only supported on surfaceless output surfaces on Mac.
         if (!use_mus)
           validator = CreateOverlayCandidateValidator(compositor->widget());
 #endif
         if (!use_mus) {
           display_output_surface =
               base::MakeUnique<GpuBrowserCompositorOutputSurface>(
-                  context_provider, vsync_callback, std::move(validator));
+                  context_provider, vsync_callback, std::move(validator),
+                  support_stencil);
         } else {
 #if defined(USE_AURA)
           std::unique_ptr<MusBrowserCompositorOutputSurface> mus_output_surface;
           if (compositor->window()) {
             // TODO(mfomitchev): Remove this clause once we complete the switch
             // to Aura-Mus.
             mus_output_surface =
                 base::MakeUnique<MusBrowserCompositorOutputSurface>(
                     compositor->window(), context_provider,
                     GetGpuMemoryBufferManager(), vsync_callback,
@@ skipping 289 matching lines @@
       gpu_channel_factory_->EstablishGpuChannelSync();
   if (!gpu_channel_host)
     return nullptr;
 
   // We need a separate context from the compositor's so that skia and gl_helper
   // don't step on each other.
   bool need_alpha_channel = false;
   bool support_locking = false;
   shared_main_thread_contexts_ = CreateContextCommon(
       std::move(gpu_channel_host), gpu::kNullSurfaceHandle, need_alpha_channel,
-      support_locking, nullptr,
+      false, support_locking, nullptr,
       ui::command_buffer_metrics::BROWSER_OFFSCREEN_MAINTHREAD_CONTEXT);
   shared_main_thread_contexts_->SetLostContextCallback(base::Bind(
       &GpuProcessTransportFactory::OnLostMainThreadSharedContextInsideCallback,
       callback_factory_.GetWeakPtr()));
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/125248 is
   // fixed. Tracking time in BindToCurrentThread.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "125248"
           " GpuProcessTransportFactory::SharedMainThreadContextProvider"));
@@ skipping 63 matching lines @@
       shared_vulkan_context_provider_ =
           cc::VulkanInProcessContextProvider::Create();
     }
 
     shared_vulkan_context_provider_initialized_ = true;
   }
   return shared_vulkan_context_provider_;
 }
 
 }  // namespace content