Create an X window overlay with static ID for GL contexts.

This code creates an X window that overlays where tab contents are drawn. The handle associated with this window never changes (unlike the X window associated with a GTK widget that is created and destroyed whenever the widget is realized and unrealized respectively).  This is helpful when creating a GL context associated with an X window. Also, having a floating overlay allows us to handle detaching GPU accelerated tabs.

This code seems to have uncovered a race condition within the GPU process. When a tab that uses accelerated compositing is detached (e.g. http://webkit.org/blog/386/3d-transforms/), the tab contents often don't get displayed even though the tab is redrawn.  A slight delay of about 100ms in the GPU process on the call to glXSwapBuffers (in gl_context_linux.cc) fixes this. To witness that GL can draw to the overlay after delay, try it with a tab with constant animation (e.g. http://webkit.org/blog-files/3d-transforms/poster-circle.html).

I've written a bare bones test (about 150 lines of C) of the overlay technique, and it requires no such delay b/w reparenting the glXSwapBuffers. I've also confirmed that there is no synchronization issues w.r.t. the X server between my patch and GL draw commands. I propose filing a new bug for the race, if this patch gets accepted.

BUG=53345,56419
TEST=Open two tabs, one with GPU rendered content (http://webkit.org/blog/386/3d-transforms/). Detach the tab with GPU rendered content.  GPU process shouldn't crash.

Review URL: http://codereview.chromium.org/3509004
Patch from Jonathan Backer <backer@google.com>.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@61561 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 31 insertions, 5 deletions

diff --git a/chrome/browser/gpu_process_host.cc b/chrome/browser/gpu_process_host.cc
index f4c6164..8e2242e 100644
--- a/chrome/browser/gpu_process_host.cc
+++ b/chrome/browser/gpu_process_host.cc
@@ -177,7 +177,7 @@ void GpuProcessHost::OnControlMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(GpuHostMsg_GraphicsInfoCollected,
                         OnGraphicsInfoCollected)
 #if defined(OS_LINUX)
-    IPC_MESSAGE_HANDLER(GpuHostMsg_GetViewXID, OnGetViewXID)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(GpuHostMsg_GetViewXID, OnGetViewXID)
 #elif defined(OS_MACOSX)
     IPC_MESSAGE_HANDLER(GpuHostMsg_AcceleratedSurfaceSetIOSurface,
                         OnAcceleratedSurfaceSetIOSurface)
@@ -210,12 +210,38 @@ void GpuProcessHost::OnGraphicsInfoCollected(const GPUInfo& gpu_info) {
 }
 
 #if defined(OS_LINUX)
-void GpuProcessHost::OnGetViewXID(gfx::NativeViewId id, unsigned long* xid) {
+
+namespace {
+
+void SendDelayedReply(IPC::Message* reply_msg) {
+  GpuProcessHost::Get()->Send(reply_msg);
+}
+
+void GetViewXIDDispatcher(gfx::NativeViewId id, IPC::Message* reply_msg) {
+  unsigned long xid;
+
   GtkNativeViewManager* manager = Singleton<GtkNativeViewManager>::get();
-  if (!manager->GetXIDForId(xid, id)) {
+  if (!manager->GetPermanentXIDForId(&xid, id)) {
     DLOG(ERROR) << "Can't find XID for view id " << id;
-    *xid = 0;
+    xid = 0;
   }
+
+  GpuHostMsg_GetViewXID::WriteReplyParams(reply_msg, xid);
+
+  // Have to reply from IO thread.
+  ChromeThread::PostTask(
+      ChromeThread::IO, FROM_HERE,
+      NewRunnableFunction(&SendDelayedReply, reply_msg));
+}
+
+}
+
+void GpuProcessHost::OnGetViewXID(gfx::NativeViewId id,
+                                  IPC::Message *reply_msg) {
+  // Have to request a permanent overlay from UI thread.
+  ChromeThread::PostTask(
+      ChromeThread::UI, FROM_HERE,
+      NewRunnableFunction(&GetViewXIDDispatcher, id, reply_msg));
 }
 
 #elif defined(OS_MACOSX)
diff --git a/chrome/browser/gpu_process_host.h b/chrome/browser/gpu_process_host.h
index e4d4559..a5268ba 100644
--- a/chrome/browser/gpu_process_host.h
+++ b/chrome/browser/gpu_process_host.h
@@ -95,7 +95,7 @@ class GpuProcessHost : public BrowserChildProcessHost {
   void OnSynchronizeReply();
   void OnGraphicsInfoCollected(const GPUInfo& gpu_info);
 #if defined(OS_LINUX)
-  void OnGetViewXID(gfx::NativeViewId id, unsigned long* xid);
+  void OnGetViewXID(gfx::NativeViewId id, IPC::Message* reply_msg);
 #elif defined(OS_MACOSX)
   void OnAcceleratedSurfaceSetIOSurface(
       const GpuHostMsg_AcceleratedSurfaceSetIOSurface_Params& params);