vr/gpu: BrowserGpuChannelHostFactory should be called on the same thread.

chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc

 // Copyright 2017 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 "chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/sys_info.h"
+#include "base/threading/sequenced_task_runner_handle.h"
 #include "cc/output/context_provider.h"
 #include "content/public/browser/android/compositor.h"
+#include "content/public/browser/browser_thread.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "gpu/command_buffer/common/sync_token.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 #include "gpu/ipc/common/gpu_surface_tracker.h"
 #include "services/ui/public/cpp/gpu/context_provider_command_buffer.h"
 #include "ui/gl/android/surface_texture.h"
 
@@ skipping 117 matching lines @@
 MailboxToSurfaceBridge::~MailboxToSurfaceBridge() {
   if (surface_handle_) {
     // Unregister from the surface tracker to avoid a resource leak.
     gpu::GpuSurfaceTracker* tracker = gpu::GpuSurfaceTracker::Get();
     tracker->RemoveSurface(surface_handle_);
   }
   DestroyContext();
 }
 
 void MailboxToSurfaceBridge::OnContextAvailable(
+    std::unique_ptr<gl::ScopedJavaSurface> surface,
     scoped_refptr<cc::ContextProvider> provider) {
   // Must save a reference to the ContextProvider to keep it alive,
   // otherwise the GL context created from it becomes invalid.
   context_provider_ = std::move(provider);
 
   if (!context_provider_->BindToCurrentThread()) {
     DLOG(ERROR) << "Failed to init ContextProvider";
     return;
   }
 
@@ skipping 12 matching lines @@
   gpu::GpuSurfaceTracker* tracker = gpu::GpuSurfaceTracker::Get();
   ANativeWindow_acquire(window);
   // Skip ANativeWindow_setBuffersGeometry, the default size appears to work.
   auto surface = base::MakeUnique<gl::ScopedJavaSurface>(surface_texture);
   surface_handle_ =
       tracker->AddSurfaceForNativeWidget(gpu::GpuSurfaceTracker::SurfaceRecord(
           window, surface->j_surface().obj()));
   // Unregistering happens in the destructor.
   ANativeWindow_release(window);
 
-  // Our attributes must be compatible with the shared offscreen
-  // surface used by virtualized contexts, otherwise mailbox
-  // synchronization doesn't work properly - it assumes a shared
-  // underlying GL context. See GetCompositorContextAttributes
-  // in content/browser/renderer_host/compositor_impl_android.cc
-  // and crbug.com/699330.
+  // The callback to run in this thread.
+  auto callback =
+      base::Bind(&MailboxToSurfaceBridge::OnContextAvailable,
+                 weak_ptr_factory_.GetWeakPtr(), base::Passed(&surface));

[mthiesse, 2017/07/05 14:45:40]

Are we just passing this surface to keep it alive? If so, please add a comment
to this effect as it looks unused and somebody might remove it later :P

[sadrul, 2017/07/05 15:05:41]

Yep, good point. Added a comment.

+  // The callback that runs in the UI thread, and triggers |callback| to be run
+  // in this thread.
+  auto relay_callback = base::Bind(
+      [](scoped_refptr<base::SequencedTaskRunner> runner,
+         const content::Compositor::ContextProviderCallback& callback,
+         scoped_refptr<cc::ContextProvider> provider) {
+        runner->PostTask(FROM_HERE, base::Bind(callback, std::move(provider)));
 
-  gpu::gles2::ContextCreationAttribHelper attributes;
-  attributes.alpha_size = -1;
-  attributes.red_size = 8;
-  attributes.green_size = 8;
-  attributes.blue_size = 8;
-  attributes.stencil_size = 0;
-  attributes.depth_size = 0;
-  attributes.samples = 0;
-  attributes.sample_buffers = 0;
-  attributes.bind_generates_resource = false;
-  if (base::SysInfo::IsLowEndDevice()) {
-    attributes.alpha_size = 0;
-    attributes.red_size = 5;
-    attributes.green_size = 6;
-    attributes.blue_size = 5;
-  }
-
-  content::Compositor::CreateContextProvider(
-      surface_handle_, attributes, gpu::SharedMemoryLimits::ForMailboxContext(),
-      base::Bind(&MailboxToSurfaceBridge::OnContextAvailable,
-                 weak_ptr_factory_.GetWeakPtr()));
+      },
+      base::SequencedTaskRunnerHandle::Get(), std::move(callback));
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,
+      base::BindOnce(
+          [](int surface_handle,
+             const content::Compositor::ContextProviderCallback& callback) {
+            // Our attributes must be compatible with the shared
+            // offscreen surface used by virtualized contexts,
+            // otherwise mailbox synchronization doesn't work
+            // properly - it assumes a shared underlying GL context.
+            // See GetCompositorContextAttributes in
+            // content/browser/renderer_host/compositor_impl_android.cc
+            // and crbug.com/699330.
+            gpu::gles2::ContextCreationAttribHelper attributes;
+            attributes.alpha_size = -1;
+            attributes.red_size = 8;
+            attributes.green_size = 8;
+            attributes.blue_size = 8;
+            attributes.stencil_size = 0;
+            attributes.depth_size = 0;
+            attributes.samples = 0;
+            attributes.sample_buffers = 0;
+            attributes.bind_generates_resource = false;
+            if (base::SysInfo::IsLowEndDevice()) {
+              attributes.alpha_size = 0;
+              attributes.red_size = 5;
+              attributes.green_size = 6;
+              attributes.blue_size = 5;
+            }
+            content::Compositor::CreateContextProvider(
+                surface_handle, attributes,
+                gpu::SharedMemoryLimits::ForMailboxContext(), callback);
+          },
+          surface_handle_, relay_callback));
 }
 
 void MailboxToSurfaceBridge::ResizeSurface(int width, int height) {
   if (!gl_) {
     // We're not initialized yet, save the requested size for later.
     needs_resize_ = true;
     resize_width_ = width;
     resize_height_ = height;
     return;
   }
@@ skipping 117 matching lines @@
   // GL_NEAREST.
   gl_->BindTexture(GL_TEXTURE_2D, texture_handle);
   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   gl_->DrawArrays(GL_TRIANGLE_FAN, 0, 4);
 }
 
 }  // namespace vr_shell