Fix errors found in Mac gn component builds

gpu/command_buffer/service/BUILD.gn

Index: gpu/command_buffer/service/BUILD.gn
diff --git a/gpu/command_buffer/service/BUILD.gn b/gpu/command_buffer/service/BUILD.gn
index 8045a03cb9a2ed6c139865069a2804c1c23e86cd..4d71c7128b1c3d72a22ef164a5fcd16f6d3ce6e4 100644
--- a/gpu/command_buffer/service/BUILD.gn
+++ b/gpu/command_buffer/service/BUILD.gn
@@ -165,6 +165,14 @@ source_set("service_sources") {
     ]
   }
 
+  if (is_mac) {
+    # Required by gles2_cmd_decoder.cc on Mac.
+    libs = [
+      "IOSurface.framework",
+      "OpenGL.framework",

[Dirk Pranke, 2015/04/15 15:48:01]

it seems like these two libraries are often needed by multiple targets in
different directories; maybe we should make them a separate target so that they
can be pulled in via deps?

[Jiang Jiang, 2015/04/15 16:17:20]

I'm not sure about that, what's needed here is completely based on the sources
of this target itself, for instance here gles2_cmd_decoder.cc is in the sources
list, that happens to use both IOSurface and OpenGL frameworks, thus we are
adding them. For other places maybe only one is used, since using one does not
necessarily mean you have to use the other.

[Dirk Pranke, 2015/04/15 16:21:07]

My point was that it seemed like there were > 2 places where we needed
specifically these two frameworks. But, I don't feel strongly about this.

+    ]
+  }
+
   if (is_android && !is_debug) {
     # On Android optimize more since this component can be a bottleneck.
     configs -= [ "//build/config/compiler:optimize" ]