GLInProcessContext: support async flushes and dedicated GPU thread

android_webview/browser/in_process_view_renderer.cc

Index: android_webview/browser/in_process_view_renderer.cc
diff --git a/android_webview/browser/in_process_view_renderer.cc b/android_webview/browser/in_process_view_renderer.cc
index 2b60bea7e39de5275359f49ba18a9bf938b72066..67ff0a73519cadcfa9d570fffdf1ef714fc31746 100644
--- a/android_webview/browser/in_process_view_renderer.cc
+++ b/android_webview/browser/in_process_view_renderer.cc
@@ -12,10 +12,13 @@
 #include "base/android/jni_android.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
+#include "base/threading/thread_local.h"
 #include "content/public/browser/android/synchronous_compositor.h"
 #include "content/public/browser/web_contents.h"
+#include "gpu/command_buffer/service/in_process_command_buffer.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkCanvas.h"
@@ -124,6 +127,31 @@ bool g_is_skia_version_compatible = false;
 
 const int64 kFallbackTickTimeoutInMilliseconds = 500;
 
+LazyInstance<ThreadLocalBoolean>::Leaky tls_gl_allowed =
+    LAZY_INSTANCE_INITIALIZER;
+
+// Called from different threads!
+static void ScheduleGpuWork() {
+  if (tls_gl_allowed.Get().Get())
+    gpu::InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread();

[piman, 2013/07/23 01:57:14]

Should this DCHECK if GL is allowed? I'm worried that otherwise we'll just spin.

[no sievers, 2013/07/25 00:41:23]

I put a TODO. I'll have to figure this out with Bo as the very next thing.

It currently somewhat works because when we only have GL from the compositor
context we cannot accumulate too much GL without eventually drawing. Also, we
eventually flush all GL if we detach the view (see OnDetachedFromWindow() below)
where we also tear down the compositor.

I want to use this also for the main webkit thread offscreen context so we can
do simple video resource management through the share group, so it definitely
cannot stay without guaranteeing a flush to happen soon.

+}
+
+class ScopedAllowGL {
+ public:
+  ScopedAllowGL();
+  ~ScopedAllowGL();
+

[piman, 2013/07/23 01:57:14]

nit: no need for blank line.

[no sievers, 2013/07/25 00:41:23]

Done.

+};
+
+ScopedAllowGL::ScopedAllowGL() {
+  DCHECK(!tls_gl_allowed.Get().Get());
+  tls_gl_allowed.Get().Set(true);
+}
+
+ScopedAllowGL::~ScopedAllowGL() {
+  tls_gl_allowed.Get().Set(false);
+}
+
 }  // namespace
 
 // static
@@ -134,6 +162,10 @@ void BrowserViewRenderer::SetAwDrawSWFunctionTable(
       g_sw_draw_functions->is_skia_version_compatible(&SkGraphics::GetVersion);
   LOG_IF(WARNING, !g_is_skia_version_compatible)
       << "Skia versions are not compatible, rendering performance will suffer.";
+
+  // TODO: There is probably a better place to do this.
+  gpu::InProcessCommandBuffer::SetScheduleCallback(
+      base::Bind(&ScheduleGpuWork));
 }
 
 // static
@@ -227,6 +259,8 @@ void InProcessViewRenderer::DrawGL(AwDrawGLInfo* draw_info) {
   }
 
   ScopedAppGLStateRestore state_restore(ScopedAppGLStateRestore::MODE_DRAW);
+  gpu::InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread();
+  ScopedAllowGL allow_gl;
 
   if (attached_to_window_ && compositor_ && !hardware_initialized_) {
     TRACE_EVENT0("android_webview", "InitializeHwDraw");
@@ -457,6 +491,8 @@ void InProcessViewRenderer::OnDetachedFromWindow() {
 
     ScopedAppGLStateRestore state_restore(
         ScopedAppGLStateRestore::MODE_DETACH_FROM_WINDOW);
+    gpu::InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread();
+    ScopedAllowGL allow_gl;
     compositor_->ReleaseHwDraw();
     hardware_initialized_ = false;
   }