Move draw call primitive type check to the API.

A part of a larger refactoring to clean up the draw call
validation.

BUG=angle:571

Change-Id: I0b220d68c04524a81ca11dc58e10c90e458cabde
Reviewed-on: https://chromium-review.googlesource.com/203771
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>

src/libGLESv2/renderer/d3d11/Renderer11.cpp

@@ -793,7 +793,8 @@ bool Renderer11::applyPrimitiveType(GLenum mode, GLsizei count)
           // emulate fans via rewriting index buffer
       case GL_TRIANGLE_FAN:   primitiveTopology = D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST;  minCount = 3; break;
       default:
-        return gl::error(GL_INVALID_ENUM, false);
+        UNREACHABLE();
+        return false;
     }
 
     if (primitiveTopology != mCurrentPrimitiveTopology)

src/libGLESv2/renderer/d3d9/Renderer9.cpp

@@ -1094,7 +1094,8 @@ bool Renderer9::applyPrimitiveType(GLenum mode, GLsizei count)
         mPrimitiveCount = count - 2;
         break;
       default:
-        return gl::error(GL_INVALID_ENUM, false);
+        UNREACHABLE();
+        return false;
     }
 
     return mPrimitiveCount > 0;

src/libGLESv2/validationES.cpp

@@ -1290,8 +1290,22 @@ bool ValidateCopyTexImageParametersBase(gl::Context* context, GLenum target, GLi
     return true;
 }
 
-static bool ValidateDrawBase(const gl::Context *context, GLsizei count)
+static bool ValidateDrawBase(const gl::Context *context, GLenum mode, GLsizei count)
 {
+    switch (mode)
+    {
+      case GL_POINTS:
+      case GL_LINES:
+      case GL_LINE_LOOP:
+      case GL_LINE_STRIP:
+      case GL_TRIANGLES:
+      case GL_TRIANGLE_STRIP:
+      case GL_TRIANGLE_FAN:
+        break;
+      default:
+        return gl::error(GL_INVALID_ENUM, false);
+    }
+
     if (count < 0)
     {
         return gl::error(GL_INVALID_VALUE, false);
@@ -1347,7 +1361,7 @@ bool ValidateDrawArrays(const gl::Context *context, GLenum mode, GLint first, GL
         return gl::error(GL_INVALID_OPERATION, false);
     }
 
-    if (!ValidateDrawBase(context, count))
+    if (!ValidateDrawBase(context, mode, count))
     {
         return false;
     }
@@ -1408,7 +1422,7 @@ bool ValidateDrawElements(const gl::Context *context, GLenum mode, GLsizei count
         return gl::error(GL_INVALID_OPERATION, false);
     }
 
-    if (!ValidateDrawBase(context, count))
+    if (!ValidateDrawBase(context, mode, count))
     {
         return false;
     }