blimp: Set up the CompositorDependencies for blimp in Chrome.

chrome/browser/android/blimp/chrome_compositor_dependencies.cc

+// Copyright 2016 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/blimp/chrome_compositor_dependencies.h"
+
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "cc/output/context_provider.h"
+#include "content/public/common/content_switches.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+#include "gpu/command_buffer/client/shared_memory_limits.h"
+#include "gpu/command_buffer/common/gles2_cmd_utils.h"
+#include "ui/android/context_provider_factory.h"
+
+namespace {
+
+void OnCompositorContextCreated(
+    const blimp::client::CompositorDependencies::ContextProviderCallback&
+        callback,
+    const scoped_refptr<cc::ContextProvider>& worker_context,
+    const scoped_refptr<cc::ContextProvider>& compositor_context) {
+  blimp::client::CompositorDependencies::ContextProviders context_providers;
+  context_providers.compositor_context_provider = std::move(compositor_context);
+  context_providers.worker_context_provider = std::move(worker_context);
+  callback.Run(context_providers);
+}
+
+gpu::gles2::ContextCreationAttribHelper
+GetOffscreenContextCreationAttributes() {
+  gpu::gles2::ContextCreationAttribHelper attributes;
+  attributes.alpha_size = -1;
+  attributes.depth_size = 0;
+  attributes.stencil_size = 0;
+  attributes.samples = 0;
+  attributes.sample_buffers = 0;
+  attributes.bind_generates_resource = false;
+  attributes.lose_context_when_out_of_memory = true;
+  return attributes;
+}
+
+bool IsAsyncWorkerContextEnabled() {
+  const base::CommandLine& command_line =
+      *base::CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableGpuAsyncWorkerContext))
+    return false;
+  else if (command_line.HasSwitch(switches::kEnableGpuAsyncWorkerContext))
+    return true;
+
+  return false;
+}
+
+}  // namespace
+
+ChromeCompositorDependencies::ChromeCompositorDependencies(
+    ui::ContextProviderFactory* context_provider_factory)
+    : context_provider_factory_(context_provider_factory),
+      worker_context_request_pending_(false),
+      weak_factory_(this) {
+  DCHECK(context_provider_factory_);
+}
+
+ChromeCompositorDependencies::~ChromeCompositorDependencies() = default;
+
+cc::LayerTreeSettings* ChromeCompositorDependencies::GetLayerTreeSettings() {
+  // MAKE THE SETTINGS!!!!!

[David Trainor- moved to gerrit, 2016/08/31 00:28:58]

yes plz!  In another patch maybe pull out the CompositorDependenciesImpl
LayerTreeSettings creator to a static helper so this can use it in the short
term?

[Khushal, 2016/08/31 21:22:51]

Done. I just moved it to internal for now, when Chrome can make the settings, we
can make it embedder provided.

+  return nullptr;
+}
+
+gpu::GpuMemoryBufferManager*
+ChromeCompositorDependencies::GetGpuMemoryBufferManager() {
+  return context_provider_factory_->GetGpuMemoryBufferManager();
+}
+
+cc::SurfaceManager* ChromeCompositorDependencies::GetSurfaceManager() {
+  return context_provider_factory_->GetSurfaceManager();
+}
+
+uint32_t ChromeCompositorDependencies::AllocateSurfaceClientId() {
+  return context_provider_factory_->AllocateSurfaceClientId();
+}
+
+void ChromeCompositorDependencies::GetContextProviders(
+    const ContextProviderCallback& callback) {
+  bool worker_context_is_valid = false;
+  if (shared_main_thread_worker_context_) {
+    // Note: If context is lost, delete reference after releasing the lock.
+    cc::ContextProvider::ScopedContextLock lock(
+        shared_main_thread_worker_context_.get());
+    if (shared_main_thread_worker_context_->ContextGL()
+            ->GetGraphicsResetStatusKHR() == GL_NO_ERROR)
+      worker_context_is_valid = true;
+  }
+  if (!worker_context_is_valid)
+    shared_main_thread_worker_context_ = nullptr;

[David Trainor- moved to gerrit, 2016/08/31 00:28:58]

What happens to any outstanding requests if this dies while we're talking to the
context provider factory?

[Khushal, 2016/08/31 21:22:50]

Good call. I think the compositor expects the worker context to be valid, so I
just added a check to make sure its still valid when we get the compositor
context back, and otherwise return null.

+
+  // Request a compositor context if the worker context is still valid.
+  if (shared_main_thread_worker_context_) {
+    HandleCompositorContextRequest(callback);
+    return;
+  }
+
+  // Add the request to the list of pending requests first, if the result
+  // comes back synchronously, the callback should get triggered.
+  pending_requests_.push_back(callback);
+
+  // If the request for a worker context is already pending, don't make
+  // another one. We'll handle all the pending requests together once the
+  // worker context is available.
+  if (worker_context_request_pending_)
+    return;
+
+  worker_context_request_pending_ = true;
+  context_provider_factory_->CreateOffscreenContextProvider(
+      ui::ContextProviderFactory::ContextType::BLIMP_RENDER_WORKER_CONTEXT,
+      gpu::SharedMemoryLimits(), GetOffscreenContextCreationAttributes(),
+      true /* support_locking */, false /* automatic_flushes */, nullptr,
+      base::Bind(&ChromeCompositorDependencies::OnWorkerContextCreated,
+                 weak_factory_.GetWeakPtr()));
+}
+
+void ChromeCompositorDependencies::OnWorkerContextCreated(
+    const scoped_refptr<cc::ContextProvider>& worker_context) {
+  DCHECK(worker_context_request_pending_);
+  DCHECK(!shared_main_thread_worker_context_);
+
+  worker_context_request_pending_ = false;
+  if (worker_context->BindToCurrentThread()) {
+    shared_main_thread_worker_context_ = worker_context;
+  }

[David Trainor- moved to gerrit, 2016/08/31 00:28:58]

What if this returns false?

[Khushal, 2016/08/31 21:22:50]

If the bind fails, then we just report the failure to the caller. And then they
can make another request if they want.

+
+  // Copy the requests first since we can get more requests as we run these
+  // callbacks.
+  std::list<ContextProviderCallback> context_requests = pending_requests_;
+  pending_requests_.clear();
+
+  for (ContextProviderCallback& context_request : context_requests) {
+    HandleCompositorContextRequest(context_request);
+  }
+}
+
+void ChromeCompositorDependencies::HandleCompositorContextRequest(
+    const ContextProviderCallback& callback) {
+  // Respond with null contexts if the worker context could not be created.
+  if (!shared_main_thread_worker_context_) {
+    callback.Run(ContextProviders());
+    return;
+  }
+
+  ui::ContextProviderFactory::ContextProviderCallback result_callback =
+      base::Bind(&OnCompositorContextCreated, callback,
+                 shared_main_thread_worker_context_);
+
+  // The compositor context shares resources with the worker context unless
+  // the worker is async.
+  cc::ContextProvider* shared_context =
+      IsAsyncWorkerContextEnabled() ? nullptr
+                                    : shared_main_thread_worker_context_.get();
+
+  context_provider_factory_->CreateOffscreenContextProvider(
+      ui::ContextProviderFactory::ContextType::BLIMP_RENDER_COMPOSITOR_CONTEXT,
+      gpu::SharedMemoryLimits::ForMailboxContext(),
+      GetOffscreenContextCreationAttributes(), false /* support_locking */,
+      false /* automatic_flushes */, shared_context, result_callback);
+}