cc: Fix interchange of red and blue content when using ETC1_RGB8_OES textures

Content is swizzled when texture format has different component order
than expected format by platform. ETC1 implies the use RGBX layout and should
not trigger a swizzle.

Updated unittest.

TEST=visual inspection with --enable-tile-compression and
PlatformColorTest.SameComponentOrder in cc_unittests

BUG=570715
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1746763002

Cr-Commit-Position: refs/heads/master@{#379533}

2 files changed, 19 insertions, 13 deletions

diff --git a/cc/resources/platform_color.h b/cc/resources/platform_color.h
index 26d6b02..67ede54 100644
--- a/cc/resources/platform_color.h
+++ b/cc/resources/platform_color.h
@@ -47,15 +47,25 @@ class PlatformColor {
     return RGBA_8888;
   }
 
-  // Return true if the given texture format has the same component order
-  // as the color on this platform.
+  // Return true if the given 32bpp resource format has the same component order
+  // as the platform color data format.
   static bool SameComponentOrder(ResourceFormat format) {
-    switch (Format()) {
-      case SOURCE_FORMAT_RGBA8:
-        return format == RGBA_8888 || format == RGBA_4444;
-      case SOURCE_FORMAT_BGRA8:
-        return format == BGRA_8888 || format == RGBA_4444;
+    switch (format) {
+      case RGBA_8888:
+        return Format() == SOURCE_FORMAT_RGBA8;
+      case BGRA_8888:
+        return Format() == SOURCE_FORMAT_BGRA8;
+      case ALPHA_8:
+      case LUMINANCE_8:
+      case RGB_565:
+      case RGBA_4444:
+      case ETC1:
+      case RED_8:
+      case LUMINANCE_F16:
+        NOTREACHED();
+        return false;
     }
+
     NOTREACHED();
     return false;
   }
diff --git a/cc/resources/platform_color_unittest.cc b/cc/resources/platform_color_unittest.cc
index 49c8353..83f65b6 100644
--- a/cc/resources/platform_color_unittest.cc
+++ b/cc/resources/platform_color_unittest.cc
@@ -21,21 +21,17 @@ TEST(PlatformColorTest, SameComponentOrder) {
       case RGBA_8888:
         EXPECT_EQ(rgba, PlatformColor::SameComponentOrder(format));
         break;
-      case RGBA_4444:
-        // RGBA_4444 indicates the number of bytes per pixel but the format
-        // doesn't actually imply RGBA ordering. It uses the native ordering.
-        EXPECT_EQ(true, PlatformColor::SameComponentOrder(format));
-        break;
       case BGRA_8888:
         EXPECT_NE(rgba, PlatformColor::SameComponentOrder(format));
         break;
+      // The following formats are not platform colors.
       case ALPHA_8:
       case LUMINANCE_8:
       case RGB_565:
+      case RGBA_4444:
       case ETC1:
       case RED_8:
       case LUMINANCE_F16:
-        EXPECT_FALSE(PlatformColor::SameComponentOrder(format));
         break;
     }
   }