Add IPC allowing GPU process to tell browser process to temporarily drop a front buffer.

This is to conserve video memory for hidden tabs that are not expected to be needed in the near term.
Review URL: https://chromiumcodereview.appspot.com/9303009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@119979 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 22 insertions, 0 deletions

diff --git a/ui/gfx/surface/accelerated_surface_win.cc b/ui/gfx/surface/accelerated_surface_win.cc
index c5c93c2..45fdf48 100644
--- a/ui/gfx/surface/accelerated_surface_win.cc
+++ b/ui/gfx/surface/accelerated_surface_win.cc
@@ -122,6 +122,10 @@ class AcceleratedPresenter {
   const int thread_affinity_;
   base::ScopedNativeLibrary d3d_module_;
 
+  // Whether the presenter is suspended and therefore unable to represent. Only
+  // accessed on the UI thread so the lock is unnecessary.
+  bool suspended_;
+
   // The size of the swap chain once any pending resizes have been processed.
   // Only accessed on the UI thread so the lock is unnecessary.
   gfx::Size pending_size_;
@@ -151,6 +155,7 @@ class AcceleratedPresenter {
 
 AcceleratedPresenter::AcceleratedPresenter()
     : thread_affinity_(g_present_thread_pool.Pointer()->NextThread()),
+      suspended_(true),
       num_pending_resizes_(0) {
   g_present_thread_pool.Pointer()->PostTask(
       thread_affinity_,
@@ -196,6 +201,8 @@ void AcceleratedPresenter::AsyncPresentAndAcknowledge(
                  size,
                  surface_id,
                  completion_task));
+
+  suspended_ = false;
 }
 
 bool AcceleratedPresenter::Present(gfx::NativeWindow window) {
@@ -203,6 +210,9 @@ bool AcceleratedPresenter::Present(gfx::NativeWindow window) {
 
   HRESULT hr;
 
+  if (suspended_)
+    return false;
+
   base::AutoLock locked(lock_);
 
   if (!device_)
@@ -265,6 +275,8 @@ void AcceleratedPresenter::Suspend() {
       base::Bind(&AcceleratedPresenter::DoResize,
                  base::Unretained(this),
                  gfx::Size(1, 1)));
+
+  suspended_ = true;
 }
 
 void AcceleratedPresenter::DoInitialize() {
@@ -499,3 +511,8 @@ void AcceleratedSurface::AsyncPresentAndAcknowledge(
 bool AcceleratedSurface::Present(HWND window) {
   return presenter_->Present(window);
 }
+
+void AcceleratedSurface::Suspend() {
+  presenter_->Suspend();
+}
+
diff --git a/ui/gfx/surface/accelerated_surface_win.h b/ui/gfx/surface/accelerated_surface_win.h
index a2b6c66..cf59178 100644
--- a/ui/gfx/surface/accelerated_surface_win.h
+++ b/ui/gfx/surface/accelerated_surface_win.h
@@ -30,6 +30,11 @@ class SURFACE_EXPORT AcceleratedSurface {
   // Synchronously present a frame with no acknowledgement.
   bool Present(HWND window);
 
+  // Temporarily release resources until a new surface is asynchronously
+  // presented. Present will not be able to represent the last surface after
+  // calling this and will return false.
+  void Suspend();
+
  private:
   linked_ptr<AcceleratedPresenter> presenter_;
   DISALLOW_COPY_AND_ASSIGN(AcceleratedSurface);