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..085f969847afd7dc8cf63446fbdb546f829e9464 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;
@@ -104,13 +112,26 @@ class EGLSyncControlVSyncProvider
   DISALLOW_COPY_AND_ASSIGN(EGLSyncControlVSyncProvider);
 };
 
+void DeinitializeEgl() {
+  if (g_initialized) {
+    g_initialized = false;
+    eglTerminate(g_display);
+  }
+}
+
 }  // namespace
 
-GLSurfaceEGL::GLSurfaceEGL() {}
+GLSurfaceEGL::GLSurfaceEGL() {
+  ++g_num_surfaces;
+  if (!g_initialized) {
+    bool result = GLSurfaceEGL::InitializeOneOff();
+    DCHECK(result);
+    DCHECK(g_initialized);
+  }
+}
 
 bool GLSurfaceEGL::InitializeOneOff() {
-  static bool initialized = false;
-  if (initialized)
+  if (g_initialized)
     return true;
 
   g_native_display = GetPlatformDefaultEGLNativeDisplay();
@@ -186,6 +207,11 @@ 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 +241,36 @@ bool GLSurfaceEGL::InitializeOneOff() {
   }
 #endif
 
-  initialized = true;
-
   return true;
 }
 
 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;
 }
 
@@ -248,7 +286,13 @@ bool GLSurfaceEGL::IsEGLSurfacelessContextSupported() {
   return g_egl_surfaceless_context_supported;
 }
 
-GLSurfaceEGL::~GLSurfaceEGL() {}
+GLSurfaceEGL::~GLSurfaceEGL() {
+  DCHECK_GT(g_num_surfaces, 0) << "Bad surface count";
+  if (--g_num_surfaces == 0) {
+    DVLOG(1) << "Destroyed last EGL surface. Deinitializing.";
+    DeinitializeEgl();
+  }
+}
 
 #if defined(OS_WIN)
 static const EGLint kDisplayAttribsWarp[] {