Add decode() functionality to image elements.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 48 matching lines @@
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "services/ui/public/cpp/gpu/context_provider_command_buffer.h"
 #include "third_party/WebKit/public/platform/WebCompositeAndReadbackAsyncCallback.h"
 #include "third_party/WebKit/public/platform/WebCompositorMutatorClient.h"
 #include "third_party/WebKit/public/platform/WebLayoutAndPaintAsyncCallback.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "third_party/WebKit/public/web/WebKit.h"
 #include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
 #include "third_party/WebKit/public/web/WebSelection.h"
+#include "third_party/skia/include/core/SkImage.h"
 #include "ui/gfx/switches.h"
 #include "ui/gl/gl_switches.h"
 #include "ui/native_theme/native_theme_features.h"
 #include "ui/native_theme/overlay_scrollbar_constants_aura.h"
 
 namespace base {
 class Value;
 }
 
 namespace cc {
@@ skipping 985 matching lines @@
 }
 
 void RenderWidgetCompositor::SetBrowserControlsShownRatio(float ratio) {
   layer_tree_host_->SetBrowserControlsShownRatio(ratio);
 }
 
 void RenderWidgetCompositor::setBottomControlsHeight(float height) {
   layer_tree_host_->SetBottomControlsHeight(height);
 }
 
+void RenderWidgetCompositor::RequestDecode(
+    sk_sp<SkImage> image,
+    const base::Callback<void(bool)>& callback) {
+  layer_tree_host_->QueueImageDecode(std::move(image), callback);

[pdr., 2017/05/18 03:20:10]

If javascript calls decode() twice on a loaded image, does that kick off two
independent decodes?

[vmpstr, 2017/05/18 18:51:12]

It issues two different promises and makes two different calls here, yes.
However, internally it will only do the decode if necessary. If it was already
locked by the previous decode, it will just succeed without doing work.

+
+  // If we're compositing synchronously, the SetNeedsCommit call which will be
+  // issued by |layer_tree_host_| is not going to cause a commit, due to the
+  // fact that this would make layout tests slow and cause flakiness. However,
+  // in this case we actually need a commit to transfer the decode requests to
+  // the impl side. So, force a commit to happen.
+  if (CompositeIsSynchronous()) {
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&RenderWidgetCompositor::SynchronouslyComposite,
+                              weak_factory_.GetWeakPtr()));
+  }
+}
+
 void RenderWidgetCompositor::WillBeginMainFrame() {
   delegate_->WillBeginCompositorFrame();
 }
 
 void RenderWidgetCompositor::DidBeginMainFrame() {}
 
 void RenderWidgetCompositor::BeginMainFrame(const cc::BeginFrameArgs& args) {
   compositor_deps_->GetRendererScheduler()->WillBeginFrame(args);
   double frame_time_sec = (args.frame_time - base::TimeTicks()).InSecondsF();
   delegate_->BeginMainFrame(frame_time_sec);
@@ skipping 123 matching lines @@
     const cc::LocalSurfaceId& local_surface_id) {
   layer_tree_host_->SetLocalSurfaceId(local_surface_id);
 }
 
 void RenderWidgetCompositor::NotifySwapTime(ReportTimeCallback callback) {
   QueueSwapPromise(base::MakeUnique<ReportTimeSwapPromise>(
       std::move(callback), base::ThreadTaskRunnerHandle::Get()));
 }
 
 }  // namespace content