Use C++11 raw string literals instead of SHADER_SOURCE macro

This is better in many ways:
1. It doesn't confuse clang format
2. \n doesn't need to be included after preprocessor directives like
   the version directive.
3. It's using built-in functionality instead of something custom.

Raw string literals should be the preferred way to include shader
source in C++ files going forward.

BUG=angleproject:2157
TEST=angle_end2end_tests

Change-Id: I8b236a6e2d5c25d920297e5bc5b5b143eddeba1f
Reviewed-on: https://chromium-review.googlesource.com/671046
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/tests/gl_tests/BufferDataTest.cpp b/src/tests/gl_tests/BufferDataTest.cpp
index e63b5b2..456b1fc 100644
--- a/src/tests/gl_tests/BufferDataTest.cpp
+++ b/src/tests/gl_tests/BufferDataTest.cpp
@@ -35,27 +35,23 @@
     {
         ANGLETest::SetUp();
 
-        const char * vsSource = SHADER_SOURCE
-        (
-            attribute vec4 position;
+        const char *vsSource =
+            R"(attribute vec4 position;
             attribute float in_attrib;
             varying float v_attrib;
             void main()
             {
                 v_attrib = in_attrib;
                 gl_Position = position;
-            }
-        );
+            })";
 
-        const char * fsSource = SHADER_SOURCE
-        (
-            precision mediump float;
+        const char *fsSource =
+            R"(precision mediump float;
             varying float v_attrib;
             void main()
             {
                 gl_FragColor = vec4(v_attrib, 0, 0, 1);
-            }
-        );
+            })";
 
         glGenBuffers(1, &mBuffer);
         ASSERT_NE(mBuffer, 0U);
@@ -253,27 +249,23 @@
     {
         ANGLETest::SetUp();
 
-        const char * vsSource = SHADER_SOURCE
-        (
-            attribute vec3 in_attrib;
+        const char *vsSource =
+            R"(attribute vec3 in_attrib;
             varying vec3 v_attrib;
             void main()
             {
                 v_attrib = in_attrib;
                 gl_Position = vec4(0.0, 0.0, 0.5, 1.0);
                 gl_PointSize = 100.0;
-            }
-        );
+            })";
 
-        const char * fsSource = SHADER_SOURCE
-        (
-            precision mediump float;
+        const char *fsSource =
+            R"(precision mediump float;
             varying vec3 v_attrib;
             void main()
             {
                 gl_FragColor = vec4(v_attrib, 1);
-            }
-        );
+            })";
 
         glGenBuffers(2, mBuffers);
         ASSERT_NE(mBuffers[0], 0U);