Fix possible IPC ordering issue caused by WebCache mojofication.

Because web_cache::mojom::WebCache::ClearCache(true) call request
is transmitted via different OS pipe with Navigation event,
maybe cause different IPC ordering with before, this CL is to fix it.

BUG=594644

Review URL: https://codereview.chromium.org/1806563004

Cr-Commit-Position: refs/heads/master@{#383065}

2 files changed, 36 insertions, 9 deletions

diff --git a/components/web_cache/renderer/web_cache_render_process_observer.cc b/components/web_cache/renderer/web_cache_render_process_observer.cc
index acf11c1..a1f1425 100644
--- a/components/web_cache/renderer/web_cache_render_process_observer.cc
+++ b/components/web_cache/renderer/web_cache_render_process_observer.cc
@@ -15,7 +15,7 @@
 namespace web_cache {
 
 WebCacheRenderProcessObserver::WebCacheRenderProcessObserver()
-  : clear_cache_pending_(false) {
+    : clear_cache_state_(kInit) {
   content::ServiceRegistry* service_registry =
       content::RenderThread::Get()->GetServiceRegistry();
   service_registry->AddService(base::Bind(
@@ -31,9 +31,16 @@ void WebCacheRenderProcessObserver::BindRequest(
 }
 
 void WebCacheRenderProcessObserver::ExecutePendingClearCache() {
-  if (clear_cache_pending_) {
-    clear_cache_pending_ = false;
-    blink::WebCache::clear();
+  switch (clear_cache_state_) {
+    case kInit:
+      clear_cache_state_ = kNavigate_Pending;
+      break;
+    case kNavigate_Pending:
+      break;
+    case kClearCache_Pending:
+      blink::WebCache::clear();
+      clear_cache_state_ = kInit;
+      break;
   }
 }
 
@@ -50,10 +57,22 @@ void WebCacheRenderProcessObserver::SetCacheCapacities(
 }
 
 void WebCacheRenderProcessObserver::ClearCache(bool on_navigation) {
-  if (on_navigation)
-    clear_cache_pending_ = true;
-  else
+  if (!on_navigation) {
     blink::WebCache::clear();
+    return;
+  }
+
+  switch (clear_cache_state_) {
+    case kInit:
+      clear_cache_state_ = kClearCache_Pending;
+      break;
+    case kNavigate_Pending:
+      blink::WebCache::clear();
+      clear_cache_state_ = kInit;
+      break;
+    case kClearCache_Pending:
+      break;
+  }
 }
 
 }  // namespace web_cache
diff --git a/components/web_cache/renderer/web_cache_render_process_observer.h b/components/web_cache/renderer/web_cache_render_process_observer.h
index aee3eac..a43f539 100644
--- a/components/web_cache/renderer/web_cache_render_process_observer.h
+++ b/components/web_cache/renderer/web_cache_render_process_observer.h
@@ -28,6 +28,12 @@ class WebCacheRenderProcessObserver : public mojom::WebCache {
   void ExecutePendingClearCache();
 
  private:
+  enum State {
+    kInit,
+    kNavigate_Pending,
+    kClearCache_Pending,
+  };
+
   // mojom::WebCache methods:
   void SetCacheCapacities(uint64_t min_dead_capacity,
                           uint64_t max_dead_capacity,
@@ -36,8 +42,10 @@ class WebCacheRenderProcessObserver : public mojom::WebCache {
   // navigation event.
   void ClearCache(bool on_navigation) override;
 
-  // If true, the web cache shall be cleared before the next navigation event.
-  bool clear_cache_pending_;
+  // Records status regarding the sequence of navigation event and
+  // ClearCache(true) call, to ensure delayed 'clear cache' command always
+  // get executed on navigation.
+  State clear_cache_state_;
 
   mojo::BindingSet<mojom::WebCache> bindings_;