Remove coverage from grpaint

BUG=skia:

Review URL: https://codereview.chromium.org/683133006
diff --git a/include/gpu/GrPaint.h b/include/gpu/GrPaint.h
index c5563f0..d44dd89 100644
--- a/include/gpu/GrPaint.h
+++ b/include/gpu/GrPaint.h
@@ -67,12 +67,6 @@
     GrColor getColor() const { return fColor; }
 
     /**
-     * Applies fractional coverage to the entire drawn primitive. Defaults to 0xff.
-     */
-    void setCoverage(uint8_t coverage) { fCoverage = coverage; }
-    uint8_t getCoverage() const { return fCoverage; }
-
-    /**
      * Should primitives be anti-aliased or not. Defaults to false.
      */
     void setAntiAlias(bool aa) { fAntiAlias = aa; }
@@ -125,7 +119,6 @@
         fDither = paint.fDither;
 
         fColor = paint.fColor;
-        fCoverage = paint.fCoverage;
 
         fColorStages = paint.fColorStages;
         fCoverageStages = paint.fCoverageStages;
@@ -140,7 +133,6 @@
         this->resetBlend();
         this->resetOptions();
         this->resetColor();
-        this->resetCoverage();
         this->resetStages();
     }
 
@@ -214,7 +206,6 @@
     bool                        fDither;
 
     GrColor                     fColor;
-    uint8_t                     fCoverage;
 
     void resetBlend() {
         fSrcBlendCoeff = kOne_GrBlendCoeff;
@@ -230,10 +221,6 @@
         fColor = GrColorPackRGBA(0xff, 0xff, 0xff, 0xff);
     }
 
-    void resetCoverage() {
-        fCoverage = 0xff;
-    }
-
     void resetStages() {
         fColorStages.reset();
         fCoverageStages.reset();
diff --git a/src/gpu/GrDrawState.cpp b/src/gpu/GrDrawState.cpp
index 1f9f696..dcf8d30 100644
--- a/src/gpu/GrDrawState.cpp
+++ b/src/gpu/GrDrawState.cpp
@@ -236,7 +236,7 @@
     this->setState(GrDrawState::kHWAntialias_StateBit, paint.isAntiAlias());
 
     this->setBlendFunc(paint.getSrcBlendCoeff(), paint.getDstBlendCoeff());
-    this->setCoverage(paint.getCoverage());
+    this->setCoverage(0xFF);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/gpu/GrPaint.cpp b/src/gpu/GrPaint.cpp
index 94ea291..56e8aa0 100644
--- a/src/gpu/GrPaint.cpp
+++ b/src/gpu/GrPaint.cpp
@@ -53,7 +53,7 @@
     // TODO: Share this implementation with GrDrawState
 
     GrProcessor::InvariantOutput inout;
-    inout.fColor = GrColorPackRGBA(fCoverage, fCoverage, fCoverage, fCoverage);
+    inout.fColor = 0xFFFFFFFF;
     inout.fValidFlags = kRGBA_GrColorComponentFlags;
     inout.fIsSingleComponent = true;
     int count = fCoverageStages.count();