Purge more cache data in RenderThreadImpl::ClearMemory

RenderThreadImpl::ClearMemory has been purging only font cache in Skia.
But, it would be good if we purge more cache data in RenderThreadImpl::ClearMemory,
because it has mainly called under out of memory. I found SkGraphics::PurgeAllCaches
purges more cache data, so this CL calls it instead of calling SkGraphics::SetFontCacheLimit.

    void SkGraphics::PurgeAllCaches() {
        SkGraphics::PurgeFontCache();
        SkGraphics::PurgeResourceCache();
        SkImageFilter::PurgeCache();
    }

Although I add a new test to measure if RenderThreadImpl::ClearMemory purges memory,
it's not completed yet. But, this CL can be covered by tests for MemoryPressureListener.
(i.e, RenderWidgetHostViewAuraTest.DiscardDelegatedFramesWithMemoryPressure.)

Bug: None
Change-Id: I6d702e02c84a04c98489bc3f20b52f55beed1452
Reviewed-on: https://chromium-review.googlesource.com/910732Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung.kim@lge.com>
Cr-Commit-Position: refs/heads/master@{#539452}

content/renderer/render_thread_impl.cc

@@ -2481,10 +2481,8 @@ void RenderThreadImpl::RecordPurgeMemory(RendererMemoryMetrics before) {
 void RenderThreadImpl::ClearMemory() {
   // Do not call into blink if it is not initialized.
   if (blink_platform_impl_) {
-    // Purge Skia font cache, by setting it to 0 and then again to the
-    // previous limit.
-    size_t font_cache_limit = SkGraphics::SetFontCacheLimit(0);
-    SkGraphics::SetFontCacheLimit(font_cache_limit);
+    // Purge Skia font cache, resource cache, and image filter.
+    SkGraphics::PurgeAllCaches();
   }
 }
 

content/renderer/render_thread_impl_browsertest.cc

@@ -20,6 +20,7 @@
 #include "base/test/scoped_feature_list.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "build/build_config.h"
 #include "content/app/mojo/mojo_init.h"
 #include "content/common/in_process_child_thread_params.h"
 #include "content/common/service_manager/child_connection.h"
@@ -36,8 +37,10 @@
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "content/public/test/test_content_client_initializer.h"
 #include "content/public/test/test_launcher.h"
+#include "content/public/test/test_navigation_observer.h"
 #include "content/public/test/test_service_manager_context.h"
 #include "content/renderer/render_process_impl.h"
+#include "content/shell/browser/shell.h"
 #include "content/test/mock_render_process.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
@@ -47,9 +50,11 @@
 #include "ipc/ipc_channel_mojo.h"
 #include "mojo/edk/embedder/embedder.h"
 #include "mojo/edk/embedder/outgoing_broker_client_invitation.h"
+#include "net/dns/mock_host_resolver.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "third_party/WebKit/public/platform/scheduler/test/renderer_scheduler_test_support.h"
+#include "third_party/skia/include/core/SkGraphics.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/gfx/buffer_format_util.h"
 
@@ -414,5 +419,37 @@ INSTANTIATE_TEST_CASE_P(
                                          gfx::BufferFormat::BGRA_8888,
                                          gfx::BufferFormat::YVU_420)));
 
+class RenderThreadImplClearMemoryBrowserTest : public ContentBrowserTest {
+ protected:
+  void SetUpOnMainThread() override {
+    host_resolver()->AddRule("*", "127.0.0.1");
+    ASSERT_TRUE(embedded_test_server()->Start());
+  }
+};
+
+#if defined(OS_ANDROID) || defined(OS_MACOSX) || defined(IS_CHROMECAST)
+#define MAYBE_ClearMemory DISABLED_ClearMemory
+#else
+#define MAYBE_ClearMemory ClearMemory
+#endif
+
+IN_PROC_BROWSER_TEST_F(RenderThreadImplClearMemoryBrowserTest,
+                       MAYBE_ClearMemory) {
+  TestNavigationObserver observer(shell()->web_contents());
+  GURL url(embedded_test_server()->GetURL("/simple_page.html"));
+  NavigateToURL(shell(), url);
+
+  EXPECT_GT(static_cast<int>(SkGraphics::GetFontCacheUsed()), 0);
+  EXPECT_GT(SkGraphics::GetFontCacheCountUsed(), 0);
+
+  // TODO(gyuyoung): How to call RenderThreadImpl::ClearMemory() from here?
+  // Instead we call same function that RenderThreadImpl::ClearMemory() calls at
+  // the moment.
+  SkGraphics::PurgeAllCaches();
+
+  EXPECT_EQ(static_cast<int>(SkGraphics::GetFontCacheUsed()), 0);
+  EXPECT_EQ(SkGraphics::GetFontCacheCountUsed(), 0);
+}
+
 }  // namespace
 }  // namespace content

content/test/BUILD.gn

@@ -847,6 +847,10 @@ test("content_browsertests") {
 
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 
+  if (is_chromecast) {
+    defines += [ "IS_CHROMECAST" ]
+  }
+
   configs += [
     "//build/config:precompiled_headers",
     "//build/config/compiler:no_size_t_to_int_warning",