CoreAnimation: Ensure frames are acked when tab capture is enabled

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <QuartzCore/QuartzCore.h>
 
 #include "base/basictypes.h"
@@ skipping 90 matching lines @@
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
 @interface NSView (NSOpenGLSurfaceResolutionLionAPI)
 - (void)setWantsBestResolutionOpenGLSurface:(BOOL)flag;
 @end
 
 static NSString* const NSWindowDidChangeBackingPropertiesNotification =
     @"NSWindowDidChangeBackingPropertiesNotification";
 
 #endif  // 10.7
 
+// Declare things that are part of the 10.9 SDK.
+#if !defined(MAC_OS_X_VERSION_10_9) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_9
+enum {
+   NSWindowOcclusionStateVisible = 1UL << 1,
+};
+typedef NSUInteger NSWindowOcclusionState;
+
+@interface NSWindow (MavericksAPI)
+- (NSWindowOcclusionState)occlusionState;
+@end
+
+#endif  // 10.9
+
 // This method will return YES for OS X versions 10.7.3 and later, and NO
 // otherwise.
 // Used to prevent a crash when building with the 10.7 SDK and accessing the
 // notification below. See: http://crbug.com/260595.
 static BOOL SupportsBackingPropertiesChangedNotification() {
   // windowDidChangeBackingProperties: method has been added to the
   // NSWindowDelegate protocol in 10.7.3, at the same time as the
   // NSWindowDidChangeBackingPropertiesNotification notification was added.
   // If the protocol contains this method description, the notification should
   // be supported as well.
@@ skipping 1305 matching lines @@
       std::string value =
           base::StringPrintf("window %s delegate %s controller %s",
               object_getClassName(window),
               object_getClassName([window delegate]),
               object_getClassName([window windowController]));
       base::debug::SetCrashKeyValue(kCrashKey, value);
     }
     return;
   }
 
+  // If the window is occluded, then this frame's display call may be severely
+  // throttled. This is a good thing, unless tab capture may be active,
+  // because the broadcast will be inappropriately throttled.
+  // http://crbug.com/350410
+  NSWindow* window = [cocoa_view_ window];
+  if (window && [window respondsToSelector:@selector(occlusionState)]) {
+    bool window_is_occluded =
+        !([window occlusionState] & NSWindowOcclusionStateVisible);
+    // Note that we aggressively ack even if this particular frame is not being
+    // captured.
+    if (window_is_occluded && frame_subscriber_)
+      scoped_ack.Reset();
+  }
+
   // If we reach here, then the frame will be displayed by a future draw
   // call, so don't make the callback.
   ignore_result(scoped_ack.Release());
   if (use_core_animation_) {
     DCHECK(compositing_iosurface_layer_);
     compositing_iosurface_layer_async_timer_.Reset();
     [compositing_iosurface_layer_ gotNewFrame];
   } else {
     gfx::ScopedCGLSetCurrentContext scoped_set_current_context(
         compositing_iosurface_context_->cgl_context());
@@ skipping 2833 matching lines @@
 }
 
 - (void)disableRendering {
   // Disable the fade-out animation as the layer is removed.
   ScopedCAActionDisabler disabler;
   [self removeFromSuperlayer];
   renderWidgetHostView_ = nil;
 }
 
 @end  // implementation SoftwareLayer