Fix some GN component build issues.

This fixes some files not compiling with the proper flags for component mode.

The device_event_log target in GN is a source set in GN and a component in GYP. This difference was causing some errors. I changed this to be a static library in GYP. It only has 2 files in it so making a whole shared library for this target seems wasteful.

Review URL: https://codereview.chromium.org/1011823002

Cr-Commit-Position: refs/heads/master@{#320805}
diff --git a/gpu/BUILD.gn b/gpu/BUILD.gn
index 75aed691..c7f70eb 100644
--- a/gpu/BUILD.gn
+++ b/gpu/BUILD.gn
@@ -36,6 +36,10 @@
 import("//testing/test.gni")
 import("//build/config/ui.gni")
 
+config("gpu_implementation") {
+  defines = [ "GPU_IMPLEMENTATION" ]
+}
+
 component("gpu") {
   public_deps = [
     "//gpu/command_buffer/client",
@@ -56,6 +60,8 @@
     "command_buffer/service/gles2_cmd_decoder_mock.cc",
   ]
 
+  configs += [ ":gpu_implementation" ]
+
   public_deps = [
     ":gpu",
     "//gpu/command_buffer/client:gles2_interface",