cc: Adding support for RGBA_4444 tile textures

ui/gl/gl_surface_egl.cc

Index: ui/gl/gl_surface_egl.cc
diff --git a/ui/gl/gl_surface_egl.cc b/ui/gl/gl_surface_egl.cc
index 8c29342ab408e2f0e10fb0ff370807d449c5646c..67e2a15629559e03aa50250bdedb237e592bad94 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -9,6 +9,7 @@
 #include "ui/gl/gl_surface_egl.h"
 
 #if defined(OS_ANDROID)
+#include "base/android/sys_utils.h"
 #include <android/native_window_jni.h>
 #endif
 
@@ -125,6 +126,11 @@ bool GLSurfaceEGL::InitializeOneOff() {
     return false;
   }
 
+  bool use_16bit_surface = false;
+#if defined(OS_ANDROID)
+  use_16bit_surface = base::android::SysUtils::IsLowEndDevice();
+#endif
+
   // Choose an EGL configuration.
   // On X this is only used for PBuffer surfaces.
   static const EGLint kConfigAttribs[] = {
@@ -138,9 +144,16 @@ bool GLSurfaceEGL::InitializeOneOff() {
     EGL_NONE
   };
 
+  static const EGLint kConfigAttribs16bit[] = {
+    EGL_BUFFER_SIZE, 16,
+    EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+    EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
+    EGL_NONE
+  };
+
   EGLint num_configs;
   if (!eglChooseConfig(g_display,
-                       kConfigAttribs,
+                       use_16bit_surface ? kConfigAttribs16bit : kConfigAttribs,
                        NULL,
                        0,
                        &num_configs)) {
@@ -155,7 +168,7 @@ bool GLSurfaceEGL::InitializeOneOff() {
   }
 
   if (!eglChooseConfig(g_display,
-                       kConfigAttribs,
+                       use_16bit_surface ? kConfigAttribs16bit : kConfigAttribs,
                        &g_config,
                        1,
                        &num_configs)) {
@@ -164,6 +177,17 @@ bool GLSurfaceEGL::InitializeOneOff() {
     return false;
   }
 
+  if (use_16bit_surface) {
+    EGLint red_size, green_size, blue_size;
+    eglGetConfigAttrib(g_display, g_config, EGL_RED_SIZE, &red_size);
+    eglGetConfigAttrib(g_display, g_config, EGL_GREEN_SIZE, &green_size);
+    eglGetConfigAttrib(g_display, g_config, EGL_BLUE_SIZE, &blue_size);
+
+    DCHECK_EQ(5, red_size);

[Sami, 2013/08/08 10:11:01]

The implementation might not support RGB565 so checking exactly for that is
probably too strict. We might get a RGBA4444 or even RGBA8888 surface.

+    DCHECK_EQ(6, green_size);
+    DCHECK_EQ(5, blue_size);
+  }
+
   g_egl_extensions = eglQueryString(g_display, EGL_EXTENSIONS);
   g_egl_create_context_robustness_supported =
       HasEGLExtension("EGL_EXT_create_context_robustness");