Infrastructure for temportarily relinquishing GPU resources.

content/browser/gpu/gpu_process_host.cc

Index: content/browser/gpu/gpu_process_host.cc
diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index be7db476b0bd1524ac6e51a8884a709403fbd2e3..34897771db48e47af14b409ff9fd9e2a63952764 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -156,15 +156,15 @@ class GpuSandboxedProcessLauncherDelegate
   ~GpuSandboxedProcessLauncherDelegate() override {}
 
 #if defined(OS_WIN)
-  virtual bool ShouldSandbox() override {
+  bool ShouldSandbox() override {
     bool sandbox = !cmd_line_->HasSwitch(switches::kDisableGpuSandbox);
-    if(! sandbox) {
+    if (!sandbox) {
       DVLOG(1) << "GPU sandbox is disabled";
     }
     return sandbox;
   }
 
-  virtual void PreSandbox(bool* disable_default_policy,
+  void PreSandbox(bool* disable_default_policy,
                           base::FilePath* exposed_dir) override {
     *disable_default_policy = true;
   }
@@ -348,6 +348,58 @@ void GpuProcessHost::SendOnIO(GpuProcessKind kind,
   }
 }
 
+// static
+void GpuProcessHost::RelinquishResources(const RelinquishCallback& callback) {
+  if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
+    BrowserThread::PostTask(
+        BrowserThread::IO,
+        FROM_HERE,
+        base::Bind(&GpuProcessHost::RelinquishResources, callback));
+    return;
+  }
+  GpuProcessHost* host = GpuProcessHost::Get(GPU_PROCESS_KIND_SANDBOXED,
+                                             CAUSE_FOR_GPU_LAUNCH_NO_LAUNCH);
+  if (!host ||
+      !BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+          base::Bind(&GpuProcessHost::RelinquishResourcesInternal,
+                     base::Unretained(host),

[jbauman, 2014/11/12 01:47:28]

I don't think this use of base::Unretained is safe. Instead just call
host->RelinquishResourcesInternal directly.

[GusFernandez, 2014/11/15 02:11:56]

This is now completely re-written and simplified in gpu_process_host_ui_shim.cc

+                     callback))) {
+    callback.Run(false);
+  }
+}
+
+void GpuProcessHost::RelinquishResourcesInternal(
+    const RelinquishCallback& callback) {
+  if (gpu_enabled()) {
+    relinquish_callback_ = callback;

[jbauman, 2014/11/12 01:47:28]

DCHECK(relinquish_callback_.is_null()); before this.

[GusFernandez, 2014/11/15 02:11:56]

Done.

+    // We send two messages to the GPU process. the first is handled by
+    // GpuChannelManager to release the default_offscreen_surface which
+    // may hold a pointer to the EGL display which is about to be released.
+    // The second is handled by the Ozone platform to release all remaining
+    // OpenGL and EGL resources. It sendsback a ResourcesRelinquished message
+    // once this is completed and it is safe for an external process to
+    // access the GPU.
+    SendGpuProcessMessage(GPU_PROCESS_KIND_SANDBOXED,
+                          CAUSE_FOR_GPU_LAUNCH_NO_LAUNCH,
+                          new GpuMsg_DeleteDefaultOffscreenSurface);
+#if defined(USE_OZONE)
+    SendGpuProcessMessage(GPU_PROCESS_KIND_SANDBOXED,
+                          CAUSE_FOR_GPU_LAUNCH_NO_LAUNCH,
+                          new GpuMsg_RelinquishDisplay);
+    return;
+#endif
+  }
+  BrowserThread::PostTask(BrowserThread::UI,
+                          FROM_HERE,
+                          base::Bind(callback, false));
+}
+
+void GpuProcessHost::OnResourcesRelinquished(bool success) {
+  BrowserThread::PostTask(BrowserThread::UI,
+                          FROM_HERE,
+                          base::Bind(relinquish_callback_, success));
+}

[jbauman, 2014/11/12 01:47:28]

reset relinquish_callback_ here. Also you should do this in
GpuProcessHost::~GpuProcessHost as well.

[GusFernandez, 2014/11/15 02:11:56]

Done.

+
 GpuMainThreadFactoryFunction g_gpu_main_thread_factory = NULL;
 
 void GpuProcessHost::RegisterGpuMainThreadFactory(
@@ -581,6 +633,8 @@ bool GpuProcessHost::OnMessageReceived(const IPC::Message& message) {
                         OnDestroyChannel)
     IPC_MESSAGE_HANDLER(GpuHostMsg_CacheShader,
                         OnCacheShader)
+    IPC_MESSAGE_HANDLER(GpuHostMsg_ResourceRelinquished,
+                        OnResourcesRelinquished)
 
     IPC_MESSAGE_UNHANDLED(RouteOnUIThread(message))
   IPC_END_MESSAGE_MAP()