Fix crash in GotAcceleratedIOSurfaceFrame

content/browser/renderer_host/compositing_iosurface_layer_mac.mm

Index: content/browser/renderer_host/compositing_iosurface_layer_mac.mm
diff --git a/content/browser/renderer_host/compositing_iosurface_layer_mac.mm b/content/browser/renderer_host/compositing_iosurface_layer_mac.mm
index 38054c855a5e65c68c07f4406ef71c7df0da6f39..81a3529f0b56c45374e82cf450818ca8d377929f 100644
--- a/content/browser/renderer_host/compositing_iosurface_layer_mac.mm
+++ b/content/browser/renderer_host/compositing_iosurface_layer_mac.mm
@@ -102,7 +102,10 @@ void CompositingIOSurfaceLayerHelper::AckPendingFrame(bool success) {
   if (!has_pending_frame_)
     return;
   has_pending_frame_ = false;
-  client_->AcceleratedLayerDidDrawFrame(success);
+  if (success)
+    client_->AcceleratedLayerDidDrawFrame();
+  else
+    client_->AcceleratedLayerHitError();
   // A trace value of 0 indicates that there is no longer a pending swap ack.
   TRACE_COUNTER_ID1("browser", "PendingSwapAck", this, 0);
 }
@@ -174,13 +177,19 @@ void CompositingIOSurfaceLayerHelper::EndPumpingFrames() {
                             iosurface
         withScaleFactor:(float)scale_factor
              withClient:(content::CompositingIOSurfaceLayerClient*)client {
+  DCHECK(iosurface);
   if (self = [super init]) {
     helper_.reset(new content::CompositingIOSurfaceLayerHelper(client, self));
 
     iosurface_ = iosurface;
     context_ = content::CompositingIOSurfaceContext::Get(
         content::CompositingIOSurfaceContext::kCALayerContextWindowNumber);
-    DCHECK(context_);
+    if (!context_) {
+      LOG(ERROR) << "Failed create CompositingIOSurfaceContext";

[Ken Russell (switch to Gerrit), 2014/08/07 22:11:44]

I wonder whether here and throughout these classes VLOG should be used instead
of LOG to reduce the amount of output emitted by default, though I realize these
are only displayed in fairly serious error conditions.

[ccameron, 2014/08/07 22:28:24]

If anything, I'd like to make these errors more visible -- I'd like them to
appear in about:gpu, if possible -- is there a way to do that in the browser
process?

+      [self resetClient];
+      [self release];
+      return nil;
+    }
 
     [self setBackgroundColor:CGColorGetConstantColor(kCGColorWhite)];
     [self setAnchorPoint:CGPointMake(0, 0)];