[Android WebView] OnMemoryPressure to drop tile memory

android_webview/browser/scoped_app_gl_state_restore.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "android_webview/browser/scoped_app_gl_state_restore.h"
 
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_surface_stub.h"
@@ skipping 47 matching lines @@
 
   glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &vertex_array_buffer_binding_);
   glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &index_array_buffer_binding_);
 
   switch(mode_) {
     case MODE_DRAW:
       DCHECK_EQ(0, vertex_array_buffer_binding_);
       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_);
       glGetIntegerv(GL_BLEND_DST_RGB, &blend_dest_rgb_);
       glGetIntegerv(GL_BLEND_DST_ALPHA, &blend_dest_alpha_);
       glGetIntegerv(GL_VIEWPORT, viewport_);
       glGetBooleanv(GL_SCISSOR_TEST, &scissor_test_);
       glGetIntegerv(GL_SCISSOR_BOX, scissor_box_);
       break;
   }
@@ skipping 120 matching lines @@
   glLineWidth(line_width_);
   glPolygonOffset(polygon_offset_factor_, polygon_offset_units_);
   glSampleCoverage(sample_coverage_value_, sample_coverage_invert_);
 
   GLEnableDisable(GL_DITHER, enable_dither_);
   GLEnableDisable(GL_POLYGON_OFFSET_FILL, enable_polygon_offset_fill_);
   GLEnableDisable(GL_SAMPLE_ALPHA_TO_COVERAGE,
                   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_);
   glStencilFunc(stencil_func_, stencil_mask_, stencil_ref_);
 }
 
 }  // namespace android_webview