[Android WebView] OnMemoryPressure to drop tile memory

android_webview/browser/scoped_app_gl_state_restore.cc

Index: android_webview/browser/scoped_app_gl_state_restore.cc
diff --git a/android_webview/browser/scoped_app_gl_state_restore.cc b/android_webview/browser/scoped_app_gl_state_restore.cc
index f72c1b4669c365d42b03f5862db98d580d6620ec..24e80f4a790b38a992d2be1a36974b6c44ed7919 100644
--- a/android_webview/browser/scoped_app_gl_state_restore.cc
+++ b/android_webview/browser/scoped_app_gl_state_restore.cc
@@ -65,6 +65,7 @@ ScopedAppGLStateRestore::ScopedAppGLStateRestore(CallMode mode) : mode_(mode) {
       DCHECK_EQ(0, index_array_buffer_binding_);
       break;
     case MODE_DETACH_FROM_WINDOW:
+    case MODE_ON_TRIM:
       glGetBooleanv(GL_BLEND, &blend_enabled_);
       glGetIntegerv(GL_BLEND_SRC_RGB, &blend_src_rgb_);
       glGetIntegerv(GL_BLEND_SRC_ALPHA, &blend_src_alpha_);
@@ -205,17 +206,23 @@ ScopedAppGLStateRestore::~ScopedAppGLStateRestore() {
                   enable_sample_alpha_to_coverage_);
   GLEnableDisable(GL_SAMPLE_COVERAGE, enable_sample_coverage_);
 
-  if (mode_ == MODE_DETACH_FROM_WINDOW) {
-    GLEnableDisable(GL_BLEND, blend_enabled_);
-    glBlendFuncSeparate(
-        blend_src_rgb_, blend_dest_rgb_, blend_src_alpha_, blend_dest_alpha_);
+  switch(mode_) {
+    case MODE_DRAW:
+      // No-op.
+      break;
+    case MODE_DETACH_FROM_WINDOW:
+    case MODE_ON_TRIM:
+      GLEnableDisable(GL_BLEND, blend_enabled_);
+      glBlendFuncSeparate(
+          blend_src_rgb_, blend_dest_rgb_, blend_src_alpha_, blend_dest_alpha_);
 
-    glViewport(viewport_[0], viewport_[1], viewport_[2], viewport_[3]);
+      glViewport(viewport_[0], viewport_[1], viewport_[2], viewport_[3]);
 
-    GLEnableDisable(GL_SCISSOR_TEST, scissor_test_);
+      GLEnableDisable(GL_SCISSOR_TEST, scissor_test_);
 
-    glScissor(
-        scissor_box_[0], scissor_box_[1], scissor_box_[2], scissor_box_[3]);
+      glScissor(
+          scissor_box_[0], scissor_box_[1], scissor_box_[2], scissor_box_[3]);
+      break;
   }
 
   GLEnableDisable(GL_STENCIL_TEST, stencil_test_);