Fix float and half float support on mobile.

src/gpu/gl/GrGpuGL.cpp

Index: src/gpu/gl/GrGpuGL.cpp
diff --git a/src/gpu/gl/GrGpuGL.cpp b/src/gpu/gl/GrGpuGL.cpp
index c899eba311f2b8485aaf3a290c0948534b35b1af..6d0613c56345353c29179a83c1998d1e02215ff2 100644
--- a/src/gpu/gl/GrGpuGL.cpp
+++ b/src/gpu/gl/GrGpuGL.cpp
@@ -2242,16 +2242,19 @@ bool GrGpuGL::configToGLFormats(GrPixelConfig config,
             break;
 
         case kAlpha_half_GrPixelConfig:
-            if (this->glCaps().textureRedSupport()) {
-                *internalFormat = GR_GL_R16F;
-                *externalFormat = GR_GL_RED;
-                *externalType = (kGLES_GrGLStandard == this->glStandard()) ? GR_GL_HALF_FLOAT
-                                                                           : GR_GL_HALF_FLOAT_OES;
+            if (this->glStandard() == kGL_GrGLStandard) {
+                if (this->glCaps().textureRedSupport()) {
+                    *internalFormat = GR_GL_R16F;
+                    *externalFormat = GR_GL_RED;
+                } else {
+                    *internalFormat = GR_GL_ALPHA16F;
+                    *externalFormat = GR_GL_ALPHA;
+                }
+                *externalType = GR_GL_HALF_FLOAT;
             } else {
-                *internalFormat = GR_GL_ALPHA16F;
+                *internalFormat = GR_GL_ALPHA;
                 *externalFormat = GR_GL_ALPHA;
-                *externalType = (kGLES_GrGLStandard == this->glStandard()) ? GR_GL_HALF_FLOAT
-                                                                           : GR_GL_HALF_FLOAT_OES;
+                *externalType = GR_GL_HALF_FLOAT_OES;
             }
             break;