Assign color=0 in GrDrawState.cpp to stop tools from raising false alarms about uninit reads.

src/gpu/GrDrawState.cpp

Index: src/gpu/GrDrawState.cpp
===================================================================
--- src/gpu/GrDrawState.cpp	(revision 7872)
+++ src/gpu/GrDrawState.cpp	(working copy)
@@ -318,10 +318,11 @@
 bool GrDrawState::srcAlphaWillBeOne(GrVertexLayout layout) const {
 
     uint32_t validComponentFlags;
-    GrColor  color;
+    GrColor color;
     // Check if per-vertex or constant color may have partial alpha
     if (layout & kColor_VertexLayoutBit) {
         validComponentFlags = 0;
+        color = 0; // not strictly necessary but we get false alarms from tools about uninit.
     } else {
         validComponentFlags = GrEffect::kAll_ValidComponentFlags;
         color = this->getColor();