Mac Video Capture: correct to float the erroneous handling of frame rate as int.

media/video/capture/mac/video_capture_device_qtkit_mac.mm

Index: media/video/capture/mac/video_capture_device_qtkit_mac.mm
diff --git a/media/video/capture/mac/video_capture_device_qtkit_mac.mm b/media/video/capture/mac/video_capture_device_qtkit_mac.mm
index 599cfac59eefb52ba42012ac42b032ad86071f02..7f4a853c63a9bde6d9b260a720a947d143f68cbc 100644
--- a/media/video/capture/mac/video_capture_device_qtkit_mac.mm
+++ b/media/video/capture/mac/video_capture_device_qtkit_mac.mm
@@ -174,7 +174,9 @@
   }
 }
 
-- (BOOL)setCaptureHeight:(int)height width:(int)width frameRate:(int)frameRate {
+- (BOOL)setCaptureHeight:(int)height
+                   width:(int)width
+               frameRate:(float)frameRate {
   if (!captureDeviceInput_) {
     [self sendErrorString:[NSString
         stringWithUTF8String:"No video capture device set."]];
@@ -185,7 +187,7 @@
         stringWithUTF8String:"Video capture capabilities already set."]];
     return NO;
   }
-  if (frameRate <= 0) {
+  if (frameRate <= 0.0f) {
     [self sendErrorString:[NSString stringWithUTF8String: "Wrong frame rate."]];
     return NO;
   }
@@ -205,7 +207,7 @@
   };
   [output setPixelBufferAttributes:videoSettingsDictionary];
 
-  [output setMinimumVideoFrameInterval:(NSTimeInterval)1/(float)frameRate];
+  [output setMinimumVideoFrameInterval:(NSTimeInterval)1/frameRate];
   return YES;
 }