FBFetch refactor + arm support

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 8474873ffff5d937f5edc2084e67e0bc5002ac17..a5053774220bf97b7e98e30181f0f32c505c5a53 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -234,8 +234,19 @@ bool GrGLCaps::init(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
     if (kGLES_GrGLStandard == standard) {
         if (ctxInfo.hasExtension("GL_EXT_shader_framebuffer_fetch")) {
             fFBFetchType = kEXT_FBFetchType;
+            fFBFetchColorName = "gl_LastFragData[0]";
+            fFBFetchExtensionString = "GL_EXT_shader_framebuffer_fetch";
         } else if (ctxInfo.hasExtension("GL_NV_shader_framebuffer_fetch")) {
             fFBFetchType = kNV_FBFetchType;
+            fFBFetchColorName = "gl_LastFragData[0]";
+            fFBFetchExtensionString = "GL_NV_shader_framebuffer_fetch";
+        } else if (ctxInfo.hasExtension("GL_ARM_shader_framebuffer_fetch")) {
+            // The arm extension requires specifically enabling MSAA fetching per sample.
+            // On some devices this may have a perf hit.  Also multiple render targets are disabled
+            GR_GL_CALL(gli, Enable(GR_GL_FETCH_PER_SAMPLE_ARM));
+            fFBFetchType = kARM_FBFetchType;
+            fFBFetchColorName = "gl_LastFragColorARM";
+            fFBFetchExtensionString = "GL_ARM_shader_framebuffer_fetch";
         }
     }
 
@@ -779,10 +790,12 @@ SkString GrGLCaps::dump() const {
         "None",
         "EXT",
         "NV",
+        "ARM",
     };
     GR_STATIC_ASSERT(0 == kNone_FBFetchType);
     GR_STATIC_ASSERT(1 == kEXT_FBFetchType);
     GR_STATIC_ASSERT(2 == kNV_FBFetchType);
+    GR_STATIC_ASSERT(3 == kARM_FBFetchType);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFBFetchTypeStr) == kLast_FBFetchType + 1);
 
     static const char* kInvalidateFBTypeStr[] = {