Infrastructure for temportarily relinquishing GPU resources.

ui/gl/gl_surface_egl.cc

Index: ui/gl/gl_surface_egl.cc
diff --git a/ui/gl/gl_surface_egl.cc b/ui/gl/gl_surface_egl.cc
index c34ca0e70e7a25396a82cd9310a90c2ef0630cd6..ee104802a69e16c51907f14d2fdfd02dddc269ff 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -62,6 +62,14 @@ EGLConfig g_config;
 EGLDisplay g_display;
 EGLNativeDisplayType g_native_display;
 
+// In the Cast environment, we need to destroy the displayType
+// returned by the GPU platform when we switch to an external app
+// which will temporarily own all screen and GPU resources.
+// Even though Chromium is still in the background.
+// As such, it must be reinitialized each time we come back to the foreground.
+bool g_initialized = false;
+int g_num_surfaces = 0;
+
 const char* g_egl_extensions = NULL;
 bool g_egl_create_context_robustness_supported = false;
 bool g_egl_sync_control_supported = false;
@@ -109,8 +117,7 @@ class EGLSyncControlVSyncProvider
 GLSurfaceEGL::GLSurfaceEGL() {}
 
 bool GLSurfaceEGL::InitializeOneOff() {
-  static bool initialized = false;
-  if (initialized)
+  if (g_initialized)
     return true;
 
   g_native_display = GetPlatformDefaultEGLNativeDisplay();
@@ -186,6 +193,11 @@ bool GLSurfaceEGL::InitializeOneOff() {
   g_egl_window_fixed_size_supported =
       HasEGLExtension("EGL_ANGLE_window_fixed_size");
 
+  // We always succeed beyond this point so set g_initialized here to avoid
+  // infinite recursion through CreateGLContext and GetDisplay
+  // if g_egl_surfaceless_context_supported.
+  g_initialized = true;
+
   // TODO(oetuaho@nvidia.com): Surfaceless is disabled on Android as a temporary
   // workaround, since code written for Android WebView takes different paths
   // based on whether GL surface objects have underlying EGL surface handles,
@@ -215,24 +227,44 @@ bool GLSurfaceEGL::InitializeOneOff() {
   }
 #endif
 
-  initialized = true;
-
   return true;
 }
 
+// static
+void GLSurfaceEGL::Deinitialize() {
+  if (g_initialized) {
+    g_initialized = false;
+    eglTerminate(g_display);
+  }
+}
+
 EGLDisplay GLSurfaceEGL::GetDisplay() {
+  if (!g_initialized) {
+    bool result = GLSurfaceEGL::InitializeOneOff();
+    DCHECK(result);
+  }
   return g_display;
 }
 
 EGLDisplay GLSurfaceEGL::GetHardwareDisplay() {
+  if (!g_initialized) {
+    bool result = GLSurfaceEGL::InitializeOneOff();
+    DCHECK(result);
+  }
   return g_display;
 }
 
 EGLNativeDisplayType GLSurfaceEGL::GetNativeDisplay() {
+  if (!g_initialized) {
+    bool result = GLSurfaceEGL::InitializeOneOff();
+    DCHECK(result);
+  }
   return g_native_display;
 }
 
 const char* GLSurfaceEGL::GetEGLExtensions() {
+  // No need for InitializeOneOff. Assume that extensions will not change
+  // after the first initialization.
   return g_egl_extensions;
 }
 
@@ -355,6 +387,7 @@ bool NativeViewGLSurfaceEGL::Initialize(
     vsync_provider_.reset(sync_provider.release());
   else if (g_egl_sync_control_supported)
     vsync_provider_.reset(new EGLSyncControlVSyncProvider(surface_));
+  ++g_num_surfaces;

[piman, 2014/11/18 20:55:34]

Could that tracking be done in the constructor/destructor of GLSurfaceEGL? That
way it'd avoid duplication.

[GusFernandez, 2014/11/19 18:50:13]

Good idea. This simplified the code somewhat.

   return true;
 }
 
@@ -365,6 +398,11 @@ void NativeViewGLSurfaceEGL::Destroy() {
                  << GetLastEGLErrorString();
     }
     surface_ = NULL;
+    DCHECK_GT(g_num_surfaces, 0) << "Bad surface count";
+    if (--g_num_surfaces == 0) {
+      DVLOG(2) << "Destroyed last (native) EGL surface. Deinitializing.";
+      GLSurfaceEGL::Deinitialize();
+    }
   }
 }
 
@@ -608,8 +646,15 @@ bool PbufferGLSurfaceEGL::Initialize() {
     return false;
   }
 
-  if (old_surface)
+  if (old_surface) {
     eglDestroySurface(display, old_surface);
+    DVLOG(2) << "Reinitialized pbuffer surface. EGL surface count remains at "
+             << g_num_surfaces;
+  } else {
+    ++g_num_surfaces;
+    DVLOG(2) << "Initialized new pbuffer surface. EGL surface count now "
+             << g_num_surfaces;
+  }
 
   surface_ = new_surface;
   return true;
@@ -621,6 +666,11 @@ void PbufferGLSurfaceEGL::Destroy() {
       LOG(ERROR) << "eglDestroySurface failed with error "
                  << GetLastEGLErrorString();
     }
+    CHECK_GT(g_num_surfaces, 0) << "Bad surface count";

[piman, 2014/11/18 20:55:34]

nit: DCHECK_GT

[GusFernandez, 2014/11/19 18:50:13]

Irrelevant after the change above.

+    if (--g_num_surfaces == 0) {
+      DVLOG(2) << "Destroyed last (pbuffer) EGL surface. Deinitializing.";
+      GLSurfaceEGL::Deinitialize();
+    }
     surface_ = NULL;
   }
 }