gpu: Bind dummy GL API when no context is current

content/common/gpu/texture_image_transport_surface.cc

 // Copyright (c) 2012 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/common/gpu/texture_image_transport_surface.h"
 
 #include <string>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 12 matching lines @@
 using gpu::gles2::MailboxManager;
 using gpu::gles2::Texture;
 using gpu::gles2::TextureManager;
 using gpu::gles2::TextureRef;
 using gpu::Mailbox;
 
 namespace content {
 namespace {
 
 bool IsContextValid(ImageTransportHelper* helper) {
-  return helper->stub()->decoder()->GetGLContext()->IsCurrent(NULL) ||
-      helper->stub()->decoder()->WasContextLost();
+  return helper->stub()->decoder()->GetGLContext()->IsCurrent(NULL);
 }
 
 }  // namespace
 
 TextureImageTransportSurface::TextureImageTransportSurface(
     GpuChannelManager* manager,
     GpuCommandBufferStub* stub,
     const gfx::GLSurfaceHandle& handle)
       : fbo_id_(0),
         current_size_(1, 1),
@@ skipping 123 matching lines @@
                                             float scale_factor) {
   DCHECK_GE(size.width(), 1);
   DCHECK_GE(size.height(), 1);
   current_size_ = size;
   scale_factor_ = scale_factor;
   if (backbuffer_suggested_allocation_)
     CreateBackTexture();
 }
 
 void TextureImageTransportSurface::OnWillDestroyStub() {
-  DCHECK(IsContextValid(helper_.get()));
+  bool have_context = IsContextValid(helper_.get());
   helper_->stub()->RemoveDestructionObserver(this);
 
   // We are losing the stub owning us, this is our last chance to clean up the
   // resources we allocated in the stub's context.
-  ReleaseBackTexture();
-  ReleaseFrontTexture();
+  if (have_context) {
+    ReleaseBackTexture();
+    ReleaseFrontTexture();
+  } else {

[piman, 2014/04/01 23:00:02]

It's not specific to this change, but this makes me think we may be leaking
resources if we lose contexts for non-GL reasons. Could you file a bug for this,
referencing this CL?

[no sievers, 2014/04/01 23:39:37]

In the stack from 355275 we are not leaking because it's called from
GpuChannelManager::OnLoseAllContexts().

We also wouldn't be leaking textures in case the context is lost because of a
parse error, because GpuCommandBufferStub::Destroy() wil still try to make the
decoder's context + surface current before calling OnWillDestroyStub().

So we could only leak if
- we don't lose the whole share group when losing contexts
- we cannot make the lost context current at all during cleanup
- there is still another context around that references the share group

[piman, 2014/04/01 23:50:58]

Only if the context isn't know to be lost, though. E.g. if the client calls
LoseContextCHROMIUM (e.g on GL_OUT_OF_MEMORY with Dana's patch), we'd set the
kLostContext state even though GL isn't lost.
That loses the whole ContextGroup, but not the whole GLShareGroup

+    backbuffer_ = NULL;
+    back_mailbox_ = Mailbox();
+    frontbuffer_ = NULL;
+    front_mailbox_ = Mailbox();
+  }
 
-  if (fbo_id_) {
+  if (fbo_id_ && have_context) {
     glDeleteFramebuffersEXT(1, &fbo_id_);
     CHECK_GL_ERROR();
-    fbo_id_ = 0;
   }
+  fbo_id_ = 0;
 
   stub_destroyed_ = true;
 }
 
 void TextureImageTransportSurface::SetLatencyInfo(
     const std::vector<ui::LatencyInfo>& latency_info) {
   for (size_t i = 0; i < latency_info.size(); i++)
     latency_info_.push_back(latency_info[i]);
 }
 
@@ skipping 247 matching lines @@
 
 #ifndef NDEBUG
   GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
   if (status != GL_FRAMEBUFFER_COMPLETE) {
     DLOG(FATAL) << "Framebuffer incomplete: " << status;
   }
 #endif
 }
 
 }  // namespace content