Plumbing explicit share groups through context creation

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

Index: content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
diff --git a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
index 52e99bc21546408ace761a6098daef49a0b268e6..c0de053cccddc5fc59ebf62785ea4d5dbbb32cae 100644
--- a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
+++ b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
@@ -237,7 +237,8 @@ WebGraphicsContext3DCommandBufferImpl::
   Destroy();
 }
 
-bool WebGraphicsContext3DCommandBufferImpl::MaybeInitializeGL() {
+bool WebGraphicsContext3DCommandBufferImpl::MaybeInitializeGL(
+    WebGraphicsContext3DCommandBufferImpl* share_context) {
   if (initialized_)
     return true;
 
@@ -246,7 +247,7 @@ bool WebGraphicsContext3DCommandBufferImpl::MaybeInitializeGL() {
 
   TRACE_EVENT0("gpu", "WebGfxCtx3DCmdBfrImpl::MaybeInitializeGL");
 
-  if (!CreateContext(surface_id_ != 0)) {
+  if (!CreateContext(surface_id_ != 0, share_context)) {
     Destroy();
     initialize_failed_ = true;
     return false;
@@ -295,15 +296,20 @@ bool WebGraphicsContext3DCommandBufferImpl::MaybeInitializeGL() {
 }
 
 bool WebGraphicsContext3DCommandBufferImpl::InitializeCommandBuffer(
-    bool onscreen) {
+    bool onscreen, WebGraphicsContext3DCommandBufferImpl* share_context) {
   if (!host_.get())
     return false;
   // We need to lock g_all_shared_contexts to ensure that the context we picked
   // for our share group isn't deleted.
   // (There's also a lock in our destructor.)
   base::AutoLock lock(g_all_shared_contexts_lock.Get());
+
   CommandBufferProxyImpl* share_group = NULL;
-  if (attributes_.shareResources) {
+
+  if (share_context)
+    share_group = share_context->command_buffer_.get();
+
+  if (attributes_.shareResources && !share_group) {
     ContextMap& all_contexts = g_all_shared_contexts.Get();
     ContextMap::const_iterator it = all_contexts.find(host_.get());
     if (it != all_contexts.end())
@@ -350,12 +356,12 @@ bool WebGraphicsContext3DCommandBufferImpl::InitializeCommandBuffer(
 }
 
 bool WebGraphicsContext3DCommandBufferImpl::CreateContext(
-    bool onscreen) {
+    bool onscreen, WebGraphicsContext3DCommandBufferImpl* share_context) {
   // Ensure the gles2 library is initialized first in a thread safe way.
   g_gles2_initializer.Get();
 
   if (!command_buffer_ &&
-      !InitializeCommandBuffer(onscreen)) {
+      !InitializeCommandBuffer(onscreen, share_context)) {
     return false;
   }
 
@@ -374,7 +380,11 @@ bool WebGraphicsContext3DCommandBufferImpl::CreateContext(
   DCHECK(host_.get());
   scoped_ptr<base::AutoLock> lock;
   scoped_refptr<gpu::gles2::ShareGroup> share_group;
-  if (attributes_.shareResources) {
+
+  if (share_context)
+    share_group = share_context->GetImplementation()->share_group();
+
+  if (attributes_.shareResources && !share_group) {
     // Make sure two clients don't try to create a new ShareGroup
     // simultaneously.
     lock.reset(new base::AutoLock(g_all_shared_contexts_lock.Get()));
@@ -424,7 +434,7 @@ bool WebGraphicsContext3DCommandBufferImpl::CreateContext(
 }
 
 bool WebGraphicsContext3DCommandBufferImpl::makeContextCurrent() {
-  if (!MaybeInitializeGL())
+  if (!MaybeInitializeGL(NULL))
     return false;
   gles2::SetGLContext(gl_);
   if (command_buffer_->GetLastError() != gpu::error::kNoError)
@@ -1192,15 +1202,27 @@ WebGraphicsContext3DCommandBufferImpl::CreateOffscreenContext(
     GpuChannelHost* host,
     const WebGraphicsContext3D::Attributes& attributes,
     const GURL& active_url,
-    const SharedMemoryLimits& limits) {
+    const SharedMemoryLimits& limits,
+    WebGraphicsContext3D* share_context) {
   if (!host)
     return NULL;
-  return new WebGraphicsContext3DCommandBufferImpl(0,
-                                                   active_url,
-                                                   host,
-                                                   attributes,
-                                                   false,
-                                                   limits);
+
+  WebGraphicsContext3DCommandBufferImpl* context =
+      new WebGraphicsContext3DCommandBufferImpl(0,
+                                                active_url,
+                                                host,
+                                                attributes,
+                                                false,
+                                                limits);
+
+  if (context && share_context) {
+    if (!context->MaybeInitializeGL(NULL)) {

[no sievers, 2013/12/10 19:53:34]

This can't be done here but has to happen on the thread where the context is
used. Specifically, it's a problem with the compositor in threaded mode and the
offscreen context provider it creates through this codepath.

It should probably be named better (BindToThread() like in l
ContextProviderCommandBuffer::BindToCurrentThread()).

[no sievers, 2013/12/11 00:36:27]

Can you maybe just pull this out by calling makeContextCurrent() in
RendererWebKitPlatformSupportImpl::createOffscreenGraphicsContext3D()?

+      delete context;
+      return NULL;
+    }
+  }
+
+  return context;
 }
 
 DELEGATE_TO_GL_5(texImageIOSurface2DCHROMIUM, TexImageIOSurface2DCHROMIUM,