Move more sources from modules.gypi to subdirectories.

third_party/WebKit/Source/modules/canvas2d/BUILD.gn

Index: third_party/WebKit/Source/modules/canvas2d/BUILD.gn
diff --git a/third_party/WebKit/Source/modules/canvas2d/BUILD.gn b/third_party/WebKit/Source/modules/canvas2d/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..095cecac110ade775ee7def91fb1ca2bc41d8cb1
--- /dev/null
+++ b/third_party/WebKit/Source/modules/canvas2d/BUILD.gn
@@ -0,0 +1,29 @@
+# Copyright 2016 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.
+
+import("//third_party/WebKit/Source/modules/modules.gni")
+
+blink_modules_sources("canvas2d") {
+  sources = [
+    "BaseRenderingContext2D.cpp",
+    "BaseRenderingContext2D.h",
+    "CanvasGradient.cpp",
+    "CanvasGradient.h",
+    "CanvasPathMethods.cpp",
+    "CanvasPathMethods.h",
+    "CanvasPattern.cpp",
+    "CanvasPattern.h",
+    "CanvasRenderingContext2D.cpp",
+    "CanvasRenderingContext2D.h",
+    "CanvasRenderingContext2DState.cpp",
+    "CanvasRenderingContext2DState.h",
+    "CanvasStyle.cpp",
+    "CanvasStyle.h",
+    "ClipList.cpp",
+    "ClipList.h",
+    "HitRegion.cpp",
+    "HitRegion.h",
+    "Path2D.h",
+  ]
+}